Genesis 35:22 states that Reuben lay with Bilhah:
It came about while Israel was dwelling in that land, that Reuben went and lay with Bilhah his father’s concubine, and Israel heard of it. (NASB)
Is it too far fetched to interpret 1 Chronicles 7:13 to say that Naphtali also lay with her?
The sons of Naphtali were Jahziel, Guni, Jezer, and Shallum, the sons of Bilhah. Emphasis mine
It cannot be deduced that Naphtali had sex with Bilhah by the Biblical texts. 1 Chronicles 7:13 is not saying that Naphtali had his children with Bilhah. Bilhah is mentioned in 1 Chronicles 7:13 because Naphtali was her second son by Jacob, according to Genesis 30:1-8. Naphtali's sons can be rightly called her sons as well. In fact, some translations render the word sons as descendants instead.
When Rachel saw that she bore Jacob no children, she envied her sister. She said to Jacob, “Give me children, or I shall die!” Jacob's anger was kindled against Rachel, and he said, “Am I in the place of God, who has withheld from you the fruit of the womb?” Then she said, “Here is my servant Bilhah; go in to her, so that she may give birth on my behalf, that even I may have children through her.” So she gave him her servant Bilhah as a wife, and Jacob went in to her. And Bilhah conceived and bore Jacob a son. Then Rachel said, “God has judged me, and has also heard my voice and given me a son.” Therefore she called his name Dan. Rachel's servant Bilhah conceived again and bore Jacob a second son. Then Rachel said, “With mighty wrestlings I have wrestled with my sister and have prevailed.” So she called his name Naphtali. (Genesis 30:1-8 ESV)
No. Only Reuven slept with Bilhah.
When it says "בְּנֵ֥י בִלְהָֽה" ("[these are the] sons of Bilhah"), it is not referring only to the four sons of Naftali mentioned in verse 13, but to all of the descendants of Bilhah mentioned, from verse 1 to verse 13.
This is parallel to the verses in Genesis 46:23-25:
וּבְנֵי־דָ֖ן חֻשִֽׁים׃ וּבְנֵ֖י נַפְתָּלִ֑י יַחְצְאֵ֥ל וְגוּנִ֖י וְיֵ֥צֶר וְשִׁלֵּֽם׃ אֵ֚לֶּה בְּנֵ֣י בִלְהָ֔ה אֲשֶׁר־נָתַ֥ן לָבָ֖ן לְרָחֵ֣ל בִּתּ֑וֹ וַתֵּ֧לֶד אֶת־אֵ֛לֶּה לְיַעֲקֹ֖ב כָּל־נֶ֥פֶשׁ שִׁבְעָֽה׃ (Westminster Leningrad Codex, Gen 46:23-25)
And the sons of Dan: Hushim. And the sons of Naphtali: Jahzeel, and Guni, and Jezer, and Shillem. These are the sons of Bilhah, whom Laban gave unto Rachel his daughter, and these she bore unto Jacob; all the souls were seven. (JPS 1917, Gen 46:23-25)
In Genesis, "בְּנֵ֣י בִלְהָ֔ה" is a summary, which includes all the previous descendants of Bilhah.
This interpretation is found explicitly in Radak:
בני נפתלי – ולא זכר מיחסו כי אם בניו ומה שאמר בני בלהה כמו שאמר בתורה אלה בני בלהה ואף על פי שלא אמר כן באחרים ויש בו דרש לשבח בלהה זכרה שברצון נשאת ליעקב שאין כתיב בה ותקח כמו בזלפה אלא ותתן. (Radak, 1 Chronicles 7:13)
Sons of Naftali – ... and what it says "sons of Bilhah", it is like it says in the Torah "these are the sons of Bilhah"... (Radak, 1 Chronicles 7:13, my translation)
