Condensation on bottom of fomies

Hi,

Just got back from a trip into the blue mountians in our camper trailer which is made out of folded checker plate and gal steel (yes its heavy and well bulit)

The floor where the fomies lie, sits directly in contact with the metal.

After a night in the cold and us lying on top of them, the bottoms of the fomies are not dripping wet but coniderably damp. We went away two weekends ago and I guess the same thing happend but I did not notice it as there was mildew build up on one of the foamies.

No.....the kids or us did not wet the bed !!!

I'm looking for solutions to try and stop this. One thought I had whilst driving home was to get som 6mm Ply to sit between the metal and fomies?

Any other suggestions? What are the floors in most camper trailers made out of as its not something I've thought to much about till now?

Thanks

Paul