Don:
I tried the gluing process in my garage, cold , about 40 degrees,, then I moved the plane into the kitchen table, ( no wife to nag me)
but had the same problem. I have just about had it with epoxy. If it wont set like it says, then I'll use Tightbond. I have never had a problem with that glue. But I do worry about fuel and it's reaction to it on stress surfaces.
I make sure I mix epoxy throughly and even add a little more hardener, same result, goey mess, never sets up. Who knows???????