I would definetly go with melamine. I would rework your dimensions and number of tubs so that way you use either 1 full sheet or 2 full sheet and theres not alot left over. Theyre 4'x8' like i said so thats 48"x96". Map out the sheets so you know exactly how to make the cuts OR have the guy at home depot make the cuts for you.
Do you already have a thermostat for it too? Because if not thats something else youll need to get.