I would get rid of the foam altogether. If you pinch the floor and get tear it is a so what. Easy to patch and you sure can't lose any value. A 35 year old boat is fully depreciated I'm thinking..I could be wrong, my wife is always saying I am.
Time is like a river. You cannot touch the water twice, because the flow that has passed will never pass again. Enjoy every moment of life on or off the river.