Good idea or not?

Just to give you a background of my unit, I own a 2006 Perma-Mount 120 Deluxe by Bane Clene.  So I was thinking of the most effective way to keep from freezing while not using a ceramic heater or spraying my brand new E-250 with insulation foam and came up with an idea of a tarp and a thermal blanket. Now before you all say I got an idea pull in the garage....  not so easy, the thing is way too big for an everyday sub-division garage. That said, I do plug in the water tank over night and the water stays around 160-200 degrees in the 120 gallon tank. The tank does put off steam through a tiny hole in the cap on top of the tank, which made me think if I could try and trap some of the steam, I would not have to use the ever so dangerous space heater. Obviously I am not concerned with the actual water tank freezing, rather the lines and the pumps, etc. So what do you think? Good idea? Please only useful comments, thank you!!

I think you are pumping way too much humidity into your van. If it ever froze you would torch to get into it. Another thing all that humidity can't be good ?

I can't really controll the humidity level.....the hole in the cap was Bane's doing, not mine. I am assuming it is there for a reason. There is not a lot of humidity to the point where persperation is forming (not even close) just enough though that I think I can use it to keep from freezing. The water tank is all insulated, so that heat does not effect the core temp of the vehicle. I am just trying to recover the warm "puff" of steam from time to time to keep everything above 32 degrees.

The hole is in the water tank so it does not collapse when you are using the water. It would create a vacuum if it could not replace the water with air as you worked.

YOU SURE YOU DIDN'T BUY A PRESSURE COOKER, MY WIFE USED TO COOK A SLAB OF BEEF IN A CONTRAPTION LIKE THAT...........BUT YOUR CONCEPT IS INTERESTING.............PROBLEM WOULD BE CONDENSATION, YOU WOULD END UP WITH A THIN LAYER OF ICE ALL OVER THE INTERIOR.

LOL if only that would work. The problem is more then height, it is length as well. I have the extended version, so height nor length will work. Welcome to my world. As far as condensation, I would have it when it was warm as well wouldn't I?  I did not experience it at all since I have plugged my van in.....and that is basically every night for three weeks. So I am wondering if I am in the clear with that?? 

iF THE VAN IS WARM AND THE STEAM COOLS TO THE AMBIANT SPACE TEMPERATURE AT A QUICK ENOUGH PACE.........THERE WOULD BE NO CONDENSATION AT THAT POINT, ESPECIALLY CONSIDERING THE HEAT GENERATED FROM THE HOLDING TANKS