I'm going to suggest an answer to my own question. It's really quite simple, but opens up a can of worms that I think is just totally awesome (and I know I'm not the only one that has this theory). Here's the "Hermeneutic" to use to process the following analysis.
The Beloved Disciple, the voice behind the Gospel of John, is Thomas Didymus, one of the twelve. Not John son of Zebedee
Doubting Thomas?! That's crazy! ... Hear me out.
Numbers 19:16 Whoever in the open field touches one who has been killed by a sword, or who has died naturally, or a human bone, or a grave, shall be unclean seven days.
And in John 20:26,
Eight days later his disciples were again in the house, and Thomas was with them.
So, the purity laws require seven days to clear out any issues in a male (like how the son is circumcised on the eighth day after impurities from the womb/blood are cleared). The fact that Thomas was presentable to Jesus and his fellow disciples only after eight days seems to solidly place Thomas' absence in the realm of Jewish purity laws.
So let's assume that Thomas was somehow ritually impure and had to be isolated from the disciples, in his own home, for his process of purification. What made him impure? And more than that, what made him impure EIGHT days ago (the day of the resurrection)?
Well, Lets look just above at ,
John 20:5, He [the disciple whom Jesus loved] bent down to look in and saw the linen wrappings lying there, but he did not go in.
John 20:8-10, Then the other disciple, who reached the tomb first, also went in, and he saw and believed; for as yet they did not understand the scripture, that he must rise from the dead. Then the disciples returned to their homes.
Here, the beloved disciple paused at the entry to the tomb. Why did he pause? I believe that he knew the purity laws deeply and kept them seriously. He knew that his next step would make him unclean for a week. He bent down and looked in and saw that it was empty. He composed himself and then accepted the consequences and walked into the empty tomb of his beloved Lord and teacher who he had, just three days earlier, watched die on the cross. He believed (that the tomb was empty) and went to his home to ritually purify for seven days.
And again we get to see the impetuous nature of Peter and his subordination to the Beloved Disciple. Just as Peter cut off the ear of Malchus in the garden, and denied Jesus, he arrived second, but just rushed headlong into the tomb without thinking or comprehending. The beloved disciple was the first and primary witness to the empty tomb, but entered second because of his sensitivity to remaining pure and the impact it would have on his life in this traumatic period.
So the beloved disciple (Thomas), the voice behind the Gospel of John, witnesses the death, empty tomb, and resurrection. These three parts affirm the witness of the death and resurrection in its entirety.
The BD testifies to the death
John 19:35, (He who saw this has testified so that you also may believe. His testimony is true, and he knows that he tells the truth.)
Here, the author wants the Beloved Disciple to be the only one at the cross to be apex follower of Christ. So instead of having a second person as a witness (John 8:17), the author adds this parenthetical comment to backup the witness.
The BD testifies to the empty tomb
Here in John 20:8-9, it says "he believed" and then immediately says "he did not yet understand that Christ must rise from the dead"
So "he believed" must refer to his validation of Mary's witness to the empty tomb. What this belief means is "he believed Mary's claim that the tomb was empty."
Now, John 8:17 says, "In your law it is written that the testimony of two [male] witnesses is valid." Here, Peter and the Beloved Disciple, are the two witnesses.
The BD (as Thomas) testifies to the resurrection
Then chapter 20 ends with Thomas's claim "My Lord and My God." It was not a "doubting Thomas" who would not believe Jesus' claim, but an "incredulous Thomas" that would not believe the other disciples who were traumatized, and had frequently not understood Jesus' teachings and had been frequently rebuked by Jesus. Thomas would have viewed the disciples as children who didn't understand these things yet.
The ENTIRE gospel "ends" here before the (later addition) of the Epilogue of chapter 21, with Thomas's declaration "My Lord and My God!" I think it is unlikely to have the book end on "see, finally that dope believed." Instead, I think it ends on, "See, even the leader of our community didn't believe until he saw for himself."
Note, that the Greek NOUN for belief/faith, pistis, appears nowhere in the Gospel of John (but all over the rest of the NT). The Greek VERB for "to believe" pisteuo appears 98 times in John, far more than in Matthew (11), Mark (14), or Luke (9). For the Fourth Gospel, belief is a PROCESS, not a THING. So the sequential process of belief through experience seems to be core. Thomas' doubting later is part of this process of developed belief through validation by experience. Empiricism!
And if you look at the beginning of the next epistle that we have in the corpus (1 John), you have a ton of validation of first person sensory experience:
1 John 1:1-3, We declare to you what was from the beginning, what we have heard, what we have seen with our eyes, what we have looked at and touched with our hands, concerning the word of life — this life was revealed, and we have seen it and testify to it, and declare to you the eternal life that was with the Father and was revealed to us — we declare to you what we have seen and heard so that you also may have fellowship with us; and truly our fellowship is with the Father and with his Son Jesus Christ.
The kind of tactile declaration of Thomas is exactly the foundational essence of the witness in beginning of 1 John.
Now of course you have the comment attributed to Jesus in John 20:29,
Jesus said to him, “Have you believed because you have seen me? Blessed are those who have not seen and yet have come to believe.”
This seems like a reactionary addition that would enable control of groups of people later as the community was fragmenting and they were giving up on their core value of individual experience. The Gospel starts with the first words of Jesus in John 1:39. Jesus invites his disciples to "Come and see." Demonstrating the linguistic anomaly of John 20:29 in the Johannine context is a topic for another post, but seems clear to me.
Another major argument against this (by Elaine Pagels in her Book Beyond Belief) is that Thomas didn't receive "the breath" to carry on the work of Christ in the world at the first meeting (John 20:22). So, without the breath, he is not a real disciple. But if Thomas is perceived as the beloved disciple, then Thomas received the breath of Christ at the foot of the cross in John 19:26,27,30 we have
When Jesus saw his mother and the disciple whom he loved standing beside her, he said to his mother, “Woman, here is your son.” Then he said to the disciple, “Here is your mother.” And from that hour the disciple took her into his own home. ... When Jesus had received the wine, he said, “It is finished.” Then he bowed his head and handed over his breath.
Here, Thomas was standing at the foot of the cross when Christ handed over the breath of his earthly life. This has Thomas as an exact continuation of the earthly work of Christ. The word for "handed over" (paradidómi) is the same word used to describe how Judas Iscariot handed Christ over to the authorities (KJV translates it as "gave up the ghost"). The word for ghost is the same word for what Jesus imparted to the disciples. Greek: pneuma = breath/spirit.
Two final things:
The Beloved Disciple being paired to the mother of Jesus as her son and she as the BD's mother (19:26) could be seen as making the beloved disciple into Jesus' twin here at the cross. "Thomas" is Aramaic for "twin," and "Didymus" is Greek for "twin."
Last thing: Of all the names used in the received text of the Gospel of John, there is only one name that appears seven times. It is Thomas (count them for yourself in the concordance). And of course, the number seven is the number of completeness and purity for the Jews, and certainly something important to the author of the fourth gospel. It would not have been lost, on the authors, where the number seven appeared.
I'll end by saying that none of these thoughts are my own. Every single idea I have comes from other places, by definition of our condition. A large portion of these ideas are articulated in Rev. Dr. Prof. James H. Charlesworth's text, The Beloved Disciple: whose witness validates the Gospel of John?. Some of them come from my own reading.