Wild idea -- skirts & a propane flame box underneath?

I'm not worried about burning up the trailer -- the heat will dissipate. And as long as the flame is outdoors, the carbon monoxide should not enter the trailer. There is no way I could seal the underbelly well enough for that to happen.

But again, the fact that no one has ever tried this is not a good sign! As we all know, one of the surest signs of impending disaster is some clown who says, "Hey, guys, watch this!!"