Replacement for foam bunk mattress

We had all new mattresses made for our TT. It was at an independent mattress maker, not one of the "store brands". They specialize in RV and commercial truck mattresses. They are foam. I am not sure what type of foam but they shape to your body and then go back to normal.

Check out the yellow pages and online for mattress manufacturers in your area.
Call a trucking company and they may be able to suggest someone local.
If that fails your next option would be to buy foam and do it yourself.