Have you had the problem since fitting your solar panels on the roof? I'd have thought they might help a bit. My 'pod's roof is still bare metal, but I wont be sleeping inside it, plus have the rooftop tent fitted, so hopefully won't be too much of an issue. If it is I'll stick some 'coreflute' (I think that's what it's called, the stuff real estate 'for sale' signs are often made of) up inside the ceiling. Had a condensation problem on the rear window of our bus, next to the bed. A couple of election 'vote for me' signs covered in fabric sorted it.
Cuppa
Ps.just ordered some of those Led's this arvo.