Small, light weight, take apart fishing pontoon

1/4 ply/foam/1/4 ply will be massively overbuilt.
You could probably just use 1/4 ply and it will work fine.

The pink insulation foam does not really help much in making the boat stiffer, since it is so easy to bend or shear. You need higher dollar foam to get some benefit.

Is 12' really enough for 2 persons, gear, and motor?
You could fit up to a 20' folding boat in the pickup - that is probably too much, but you get the idea.

 

Yeah thinking I might just go with the 1/4" on the sides and glass inside and out, but am going to go with the sandwich construction on the bottom with wood ribs inside the sandwich too. I think the foam sandwich bottom does give it better flotation and rigidity. I guess I could make it a 14', would still only be 7' folded, I have a short box truck with a toolbox at front of bed, but even so with the tailgate down it would only stick out about a foot beyond the tailgate.