Condensation inside any TC (or for that matter any RV) is an INDIRECT result of not much insulation but more so a direct result of a tight living space (homes breathe through air infiltration RV's don't) coupled with the human occupants aspirating moisture from their bodies and cooking which gives off a large amount of moisture not just from the boiling water but from the propane burners themselves and has no where to go but condense on the cold walls, windows and ceiling and places you cannot see...under the wallboard, on the frame structure and in the insulation that's under the wallboard, all contributing the the eventual demise (rotting) of the unit.
The cold water glass example on a hot day. Water condenses on the outside of the glass.. An RV is cold on the outside and inside walls, occupants and cooking gives off moisture. Moisture condenses on the cold surfaces. Simple really and the answer is simple too.
You need to vent to the outside at all times when in the unit. Know thats counter productive, you are heating the space to keep warm but you have to vent off the inside humidity od bad thins will happen. Might take a while but it will eventually degrade the unit.
Far as winter camping goes, My furnace keeps out pop up very comfortable no matter what the ambient outside temp is. We typically keep the inside temps at 65 during the day and 60 at night, we sleep under a down blanket but at all times the ceiling vents are open a bit and at least one lower window is cracked open as well even though the tent is closed up and the windows on the tent have reflectix over them.
Haven't been out this winter but I was last winter on my Northern Michigan property in sub freezing temps with no issue other than using quite a bit of propane for heat. Glad I run twin bottles. Over the course of 3 days I went through one and a half bottles.
Only difference between a pop up and a hardside is the upper 1/4th is canvas. Other than that, no difference. Roof is the same as, as are the sides and the bottom... and of course the same issues (condensation) appear, just like any other RV and you deal with them in exactly the same way, by venting the interior humidity out.
To me, the big advantage is of course a lower vertical Cg, much less wind resistance at speed, easier storage in the off season and an overall lower unit weight. Unless you have a commercial type garage, you ain't getting your TC inside. I put mine in my garage next to the truck in the winter. Inside, protected from the elements and not outside, all pluses in my view.
