Carpet on fiberglass ceiling? Condensation?

Hi folks!

My new van has a fiberglass high top, lined with carpeting. I am wondering if I should tear out the carpet and just paint it.

This would be a lot easier to do now, in the build stage, rather than after the interior is finished and I am actually camping in the van. But that means I cannot experiment, so I am hoping to learn instead from you all's experience instead.

I've done most of my camping in deserts. But I spent part of this past winter near the Oroville Dam -- a humid climate all the time, and crazy wet this year. And I might go back.

The thing about that climate is it is humid and TEMPERATE-- about 65 in winter. So I really don't want to run a OR heat, either of which would dry things out a little.

My current van has a carpeted floor. (No, not shag! Stock automotive floor stuff.) I keep it covered with plastic mats, but this winter had endless problems with condensation under the mats.

This convinced me of the importance of a non-permeable floor in the new van. But how will carpet behave on the ceiling?

Clearly it will absorb condensation, and then dry out as circumstances permit, ideally daily. And it will add some insulation. But in areas with poor air circulation (storage), will the ceiling carpet stay damp, and mold like my flooring did?

What if I have just a painted fg ceiling? In humid cold weather (no ac) will there be enough condensation to drip or run? That would also be onto storage areas.

I sure could use some info from you folks, especially any with fiberglass shells. What does your rig do, and in what climates?