RE: More Gorilla glue questions
If you can't get a clamp on the parts, try putting a few small dabs of medium CA on the parts in addition to the poly glue. The CA will set quickly and hold the parts together. Then as the poly expands, it won't lift the part. You'd need to use some caution and common sense with this technique, but I've used it before and it works fine.
Yes, poly will work well as a fillet. It is lighter than CA and Epoxy, but I'd still use minimal glue. I'd suggest making a tool (i.e. a stick), to help spread a small quantity directly in the corner. You can accelerate/increase the foaming by lightly misting with water.
Cheers.