Insulation question

Thanks everyone. It looks like foam sheets may be the way to go. I'm a little gun shy with moisture given the repairs I'm making now and am thinking watertight isn't the way to go. My trailer was leaking through the roof and rear wall and the water was trapped in the underbelly ( I had to cut the fabric to let it drain).

I've also used rock wool insulation around the fireplace and have a bags around that I would use if I feel like doubling up.