: I'd shy away from the contact cement and sillycone. Don't know what contact
: cement you're using, I used the yellow DAP stuff to glue my foam seat and
: backrest in, and it works alright, but I've had to re-glue some also. It's
: water resistant, but sometimes lets go. If you're stashing ~$500 worth of
: electronics inside, I'd probably still consider putting them in heavy
: ziplocs or a little dry bag. Water's some wet stuff.

I was using the two plastic tubs to build the wood strip tube shape that the flange for the lid will be glued to. I may cut the plastic tub off lower then the flange for extra holding power. Now I need a few days to fiberglass the inside and out and make a back for the end of the tube.
I will look for the sealant 3M 5200 you mentioned. My experiments with silicone failed. I applied it on top of dried Weldood contact cement and it wouldn’t stick, then I applied it to wet Weldwood contact cement and that was better but not good enough. I do think contact cement applied to the bottom of the plastic flange and the end of the strips will work OK. Then brush on contact cement around the edge of the flange and strips where they meet for extra waterproofing and holding power. Anyway I will start that way and see if it holds. Good Idea to put the expensive stuff in zips just to be safe.
John