Canopy/Topper insulation

I've had several truck canopies over the years and they all had carpet or some kind of insulation on the underside of the roof.
Now I'm looking at some commercial models and they sometimes charge a lot for insulation. So I'm considering just leaving it bare fiberglass.

I don't plan on ever sleeping back but I'm curious as to whether the canopy is going to sweat on the underside without insulation if it's damp back there? (they always leak so I figure it will be damp..)
Anybody have experience in a damp area with this?

Thanks in advance.