With that vent in there it is gonna get cold.

I have a cieling with insulation on top. I had the sweaty airplane
problem but put in a cieling fan and things have been fine since. It has
not been turned off in 8 years! (2 actually)But with the air moving, it
can hold a lot more moisture and won't condense out. With my entire
hangar insulated the temperature does not get below freezing in the
winter. And it is cool in the summer also. The cieling fans are
fantastic! Also the floor is epoxy painted perhaps keeping out ground
moisture.