RV Mattress - mildew problems

When I still lived up North I had same problem.

What I found was with the cold temps and then warm up condensation sometimes builds up under mattress where it touches the wood base. Because each is a different temperature when the temps outside are warming up.

It doesn't really mold up it just gets damp which gives you that mildew.

I have allergies so the first time that happened I had to throw out the mattress.

What I did was put four big empty 5 gal paint buckets on each corner and lifted the mattress on top of them for when MH was in storage for the winter. No more moisture problems.

You can try febreezing the heck out of it and letting it air out in the dry sun. Sometimes that works.

For future, you might use damprid to keep the moisture down in your RV. I use the big tub and it lasts about 3 months in my 21ft rig. It really helps with condensation, etc.

I've seen this discussed in the past and IIRC, it seems to have something to do with heat from the engine.
I don't think you'll ever get rid of the musty smell entirely without replacing the mattress. Then I would install some high R value rigid insulation under it.

Depends on the size of the support. I'd also be investigating the cause of mildew/moisture. That's not good.

A standard queen will work. I think they at 60 x 70.