I wouldn't choose that foam/vinyl "marine" product, personally, because it is (typically) an open-celled foam on the back. This means that it can soak up water/condensation. I would use Ensolite (or similar), because it is closed-cell foam, and won't soak up water. I think this is preferable for the inside of a camper (or a boat, for that matter).
I'm not sure how the insulation compares, but I wouldn't be surprised if the Ensolite has more insulative value (but that would bear checking).
IR Foam Specialty (linked to the left or searchable) sells Ensolite-type foam. I don't think they sell the kind with the white facing though, so you would probably paint
it (but there may be such a faced product available). If you are ordering Ensolite from IR Foam, you can also get it slightly thicker than the original 3/16" if you want to. I would think 1/4" would still be plenty conformable.