A very wide range of products used. Interesting. What prompted me with this I was cleaning down my camper with a hose and soft brush in the front yard with a ordinary blue tarp under the main tent. Even tucked the extra trap outside the floor area under the canvas so it would not pool. I still found I had a significant amount of moisture/water under the PVC camper floor when I packed it up the next day after being in the hot sun. It obviously trapped between the tarp and camper floor.
Oz Trail Ultramesh sounds interesting.