well, "epoxy" is a general term, really. smc/fiberglass, or fiberglass repair, etc adhesive from a paint/body supply store will get it done permenantly, andyou can still unbolt it. tell them the situation, and they will hand you one of the 300 different kinds they have. go for the longest cure time that you can allow before the show, but they have stuff that is ready in little as 1/2 hour. nothing else mentioned would hold a candle to lord/fusor....not even gorrila glue. anything else you put in there now may/will make the later repair exceedingly difficult. as for the leaking, you can just cut yourself a new rubber or foam gasket, or you may find that it's actually cheap at the dealership. fyi- i used to own a body and equipment shop with a partner, so i know how well this stuff works.
good luck-
-heath H-