fish box insulation

[huntndakota]

My marathon has a "fish box" the whole width of the boat above the motor and almost all of the insulation is worn off on the outside. I was wondering what kind of spray on insulation would work the best and be able to handle to heat? Also what exaclty would this box be good for is 6' long 10" wide and 7"deep? I was just going to use it for drinks on ice since it has a drain in it.