Before you put anything back up, you want to determine if the mold was a result of humidity trapped in the trailer or a leak. In what part of CA are you? Was the mold localized or all over?
If you suspect a leak, a garden hose on a dry day, working from the bottom up, can pinpoint the source.
If it's humidity, there are a number of solutions, including ventilation, chemical desiccants, electric dehumidifiers...
Closed cell foam makes a good insulator. Since it's just a narrow strip on a
Burro, you could trim it with whatever suits your fancy. Get creative, but stick with something non-absorbent. I saw the bamboo solution, too, and it looked nice. Marine headliner, ceiling tin, lime green shag carpet...
Okay, maybe not the carpet... [emoji3]