[cookinwitdiesel]

Just an FYI, skirting the trailer is to make a static air gap which helps insulate the underside of the trailer. If it is open, you will constantly lose energy through the floor, but if that area is not free flowing, than once the air is warmed some, it creates a barrier between your floor and the truly cold outside air. It is the same principle of why bridges freeze over before surface roadways, the air passing underneath them constantly pulls out energy dropping their temperature.

So the air itself is providing the insulation - the foam skirt is just to keep that air in.