Convenient, as I had a chance to fully test the Propex system. In one word - WOW!
When I finally checked out after midnight, the Scouts still going strong, I crawled into the back of the Thingamajigger and turned on the Propex. It was 30 degrees outside, and within minutes the van was a comfy temp. It was just me, so I did not have the top up.
During the night I needed to turn the heat down, as I had it too high to compensate for the cool start and myself needing to thaw out. The Propex was maintaining too warm a temperature within the Thingamajigger. Once I did, the unit kicked on and off as needed to maintain a perfect temperature.
What a great addition to the van!