Finally Finished!
The weather really put me in a hole, but here it is.
I used Lexan for the mounting board, taped it off and sprayed the back with red and black paint for a little different look.
I took small blocks of the lexan and glued them together, then used epoxy to attach them to the fiberglass where I cut out smap squares of carpet. I tried to epoxy the large board to the small blocks but that did not work so I drilled holes in the blocks and used 5/8 inch #10 screws to attach the board to the blocks.
Sounds great, had it running today and my neighbir 4 houses a way came out thinking it was the kid between us working on his car stereo. He was ready to light him up and had to pause when he saw me jamming in the boat.