This almost touches on the very notion of the Eucharist and the body of Christ.
Either the difference between ‘in’ and ‘on’ matters a very great deal, or the Question should be valued on the difference. Which works for you?
Where could ‘I bear on my body the brand-marks of Jesus’ come from? Various Answers and Comments here suggest the Question is resolved by brand marks yet where has it been suggested anyone ‘… bore on his body the brand-marks of Jesus’… whether that meant literal iron-branding marks or not?
That the Greek preposition, ἐν, is correctly translated as ‘in, on, among’ suggests at best that the translator ignores the context. Could that be helpful?
If Paul had more precise language available, what exactly might he/that have said?
Can you say how anyone ‘obviously elected’ anything? How do you know he didn’t use those words simply for lack of further thought?
Who doubts Paul's bodily scars from beatings and other experiences should be on, not in, his body?
Doubtless Greek ‘stigma’ denotes a mark on the flesh… ‘More summarily’ adds what but confusion?
The Pulpit commentary seems much more tenuous. When you say ‘I am one who bear branded on my body…’ should that be ‘I bear…’ or ‘I am one who bears…’? That I never heard of anyone bearing ‘flesh-marks of Jesus’ matters little. What matters is that your translation was wrong, invalidating anything based upon it.
ἐγὼ is inserted with emphasis means what, in English? Unless you want to exclude all but scholars of Greek, please first at least present ἐγὼ in the Roman alphabet and then provide a clear translation, remembering that ἐν, means ‘in, on, among’ only by context.
How could it matter that being such as he here describes himself, he had a claim upon his brethren to be spared unnecessary annoyance… even if that was rendered in proper English?
You might claim that ‘proper English’ was a niggle and isn’t the real Question how close anything comes to the heart of Christianity in any language?