I've posted this many many times over the years ...
... IF you are going to glue, use the proper "soft setting" glue like Upholsterers' Landau Top Adhesive, RV Rubber Roof Adhesive, and some have had excellent results with Sikaflex or PL Urethane Adhesive (but, I can't testify to any results, personally) ... then proper preparation of the aluminum and the surface (cleaning all dirt & oils off both surfaces with lacquer thinner is good) ... then proper and even application of the glue. I NEVER glue the roofs of my TDs, only the sides ... and in over 25 years of gluing on my sides, I've yet to have one separate!
It IS an expensive proposition to remove & properly replace delaminated skins (unless the mfg. is honorable enough to admit their mistakes and fix it), so if you CAN live with the bulging until it all has separated, I would recommend that (but DO check all the moldings & seams to make sure they're still sealed).
Good Luck, and in the meantime ...
CHEERS!