Before fretting too much about preserving curvature etc, perhaps try to remove one?
I tried mine and they were "bonded " (Sikkaflex or similar?) As well as wood-screwed...fearing damage, I gave up,and hand scraped/sanded in place.
I removed the screws and caps to make the task much easier, the rails remained attached.
They are now bare teak, treated with Boracol same as decks and cabin top handrails (similarly bonded and screwed down.) Giving a pleasing (to me) silver grey natural finish which is easily maintained.