There isn't any "glue" fix that isn't cost/labor intensive. We had the ceiling fall in our '97 due to adhesive failure (due to EPA regs the glue used then fails at 95f). The past Pres of the Georgia Unit, Warren Fore, has templates to screw the ceiling back up with a pattern which makes it look almost quilted. It looks good, is affordable, and permanent. I realize you are in Canada, but he goes to a lot of the rallys and other events. I don't think he is on Airforums, but you can reach him through the Top of Georgia website.
Craig and Carol
1997 34' Excella 1000
1970 27' Overlander, International
2009 Ford F150 5.4L
ProPride hitch with 1400# bars
Past President Southeastern Camping Unit (12)