My first thought when reading your post was that the 6.5 Creedmoor is just fine for PRS, and is actually coming back into favor with a lot of shooters.
That said, I've used permanent thread locker (red Loctite) to do something like what you're thinking of, and it worked fine.
This was with Savage threaded pre-fits from Northland, their precision ground barrel nut, and a Zermatt action. The thread locker goes on in place of grease between the barrel and nut (but not on the threads that go into the action!). One obviously must be careful to keep Loctite out of the action, and must be comfortable setting headspace, but it did work and the two barrels I did this with (a Dasher and 223 AI) maintained headspace and would return to with a few tenths of zero when swapped. The nuts can be removed with the aid of a torch if it doesn't work out to your satisfaction. Ideally one would also have a gunsmith either thread the nut for set screws or pin the nut in place.
I got the idea from a long time member (reubenski) who has since deleted his account, and with it all of his posts.
Still, I much prefer shouldered barrels. Gluing barrel nuts on was an interesting experiment because I already had the parts on hand to try it. Every barrel I've purchased since has either been a shouldered pre-fit or a premium blank cut to the action by y gunsmith.
If you can, my advice would be for your new 6mm BR barrel to be shouldered.