are you sure you dash vent door is closing ? It sounds like it might be staying open and not redirecting to the other vents (defrost or floor) even though they're open too.
So you plan on keeping your soft top and letting him keep the hard top ? I'd keep the hard top if it was me. I don't know about up there, but here hard tops are like gold
either take a boroscope with you or atleast stick your finger in the hole in the frame just in front of the back tire and feel around. that will tell the tale. A scope is best but you can tell if the inside surface is smooth with your finger.