Want to put foam under the wood floorboards in my small jon. Each piece would only be about 34" long x 18" or so wide by 1.125" thick. I would need a few pieces. I've seen sheets of plain Styrofoam, blueboard, and some pink colored blueboard like foam at the Lowes/Menards etc. Boat is electric motor only, so no problems with spilled gas melting the foam. What is the best and most economical sheet type foam to use?