Worthwhile to insulate/enclose underbelly without heating?

Prof, what heat source are you planning on using in the living area? If you install a buddy type heater o a Camco Wave, even the smallest size to keep you warm, it then would be pretty simple cut a hole to install a very small fan to circulate a little of that heat below you.
The fan could be as small as the ones used for circulating air in the fridge, and blowing a little air out of the living space will help provide a little fresh air flow from outside for safety with the heater.