jaysOn - Guess the heating and rolling the boulder into the tent trick will not work for you
Never understood why Tepui chose to make an alloy base to their tents. We use alloys as heat sinks, most of your heat is lost through the bottom of the tent because of your contact. Moisture condenses on metals well so maybe it performs as a dehumidifier once you get the mattress off the base.
Don't know why Zodi isn't making their little tent heater these days. Probably a product liability thing, they are crude but effective. For a roof tent, I have thought these are great, turn them on to heat and dry out the tent before you go to sleep and and then turn it off, turn it on in the morning to warm up. A buddie of my built a nice hook system for my tent to hang the heater outside away from tent.
Here is a link to Zodi -
http://zodi.com/tent-heaters/hot-vent-tent-heater - no affiliation
and they do show up on eBay from time to time, again a link -
http://www.ebay.com/itm/ZODI-Propane-Hot-Vent-Tent-Heater-/291628700100?hash=item43e66cd1c4:g:xsQAAOSwp5JWXRDy - again, no affiliation
The last wild idea is one that came from an associate that went long. We used to go to a lot of trouble to work with fabric companies to get the vapor transportation right but with so many tents coming from China now, I don't think they really care so moisture is retained inside these newer tents. What I'm saying is this will work with older tents, I don't know about the new "replica" tents. So, with that caveat, go and buy a 12 volt heated blanket, the type they sell at truck stops and put it in the tent when it is closed. Then run the wire down to your vehicle and turn it on during the day when you are driving. They warm up the tent and force the residual moisture out. When you open the tent, it is warm and dry inside. Don't try running a blanket for the night, they draw a lot of power. The best system if you want to throw money at the problem is to get a 12 volt heated mattress pad that lies under your mattress.