[Steveo57]

I've taken the coroplast off mine and installed a layer of reflectix when I put it back up. I cut the coroplast into three sections and added some PT 1x4 at the seams to give me something to screw the seams down tight. Then taped up the seams also. Mine just has a 2" duct coming off the furnace that drops into the underbelly so not a lot of heat gets down there but if you seal up the underbelly good (better than what you get from the factory) it should work better than nothing. The other thing I did was to insulate the PEX water pipes to try and help out.

I'll have to check into leaving an exhaust path for the warm air. I sealed up all the holes into the trailer as a second barrier in case something gets into the underbelly. Might consider putting a screened vent somewhere.