12 I must go on boasting. Although there is nothing to be gained, I will go on to visions and revelations from the Lord. 2 I know a man in Christ who fourteen years ago was caught up to the third heaven. Whether it was in the body or out of the body I do not know—God knows. 3 And I know that this man—whether in the body or apart from the body I do not know, but God knows— 4 was caught up to paradise and heard inexpressible things, things that no one is permitted to tell. 5 I will boast about a man like that, but I will not boast about myself, except about my weaknesses
(2 cor 12:1-5)
And he connects with this supreme revelation the his thorn in the flesh:
Even if I should choose to boast, I would not be a fool, because I would be speaking the truth. But I refrain, so no one will think more of me than is warranted by what I do or say, 7 or because of these surpassingly great revelations. Therefore, in order to keep me from becoming conceited, I was given a thorn in my flesh, a messenger of Satan, to torment me. 8 Three times I pleaded with the Lord to take it away from me. 9 But he said to me, “My grace is sufficient for you, for my power is made perfect in weakness.” Therefore I will boast all the more gladly about my weaknesses, so that Christ’s power may rest on me. 10 That is why, for Christ’s sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong.
So this particular revelation in the third heaven implies the thorn.
In Gal 2, Paul talks about this sharing of the suffering of the Christ:
19 “For through the law I died to the law so that I might live for God. 20 I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me. 21 I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!”
Could the thorn in the flesh be the particular sign by which Paul had "been crucified with Christ" ?