It is called ensolite or sometimes referred to as elephant skin. As a fellow renovator of a
Surfside. Welcome. Lots of info on this forum. Not sure where you can get ensolite, though there are others on the forum who have managed to acquire it. A lot of
boler owners use reflectix when they renovate and I have even seen those colored foam tiles used since they are a closed cell foam like ensolite. Folks are quite creative. If you are looking for general information regarding a
surfside reno, I have found Surfside Refit Saga by PeterH on this forum to be very helpful and informative. If your ensolite inside the trailer is just dirty, it can be cleaned and painted with a latex painted. That's what we did. The seam tape can be removed and filled with a paintable caulk and if you need to patch you may be able to steal from inside the benches, closets or around the wheel wells where no one will see. Replace that with reflectix, fill your patch seams with caulk and texture the caulk with a sponge before it sets . Good luck