It seems to me that the only way to safely use the LP burners in the van
for heat would be by fabbing up an arrangement that resembled those big
gas shop heaters.  You know the ones.  They hang suspended from the ceiling
and when heat is called for the propane starts flowing through long,
vertical grids that are vented outside.  These grids have a fan behind 
them that blows cool air past the grid, heating the air and the space.

_If_ I were to attempt such a beast, it would have a base that girdled the
burner(s), have a high-temp seal on the bottom and have some means of
attaching to the stainless top, such as screws to hold it down tight.

There would be several (5-10) tubes running vertically, attached to the
base with a thread/double nut arrangement.  The tubes might be staggered
to the airflow from the fan, they might be aligned.  Some kind of collector
at the top of the tubes would collect the discharge from the burner(s)
and send it out a small chimney, permanently attached to the roof, through
a pipe between the collector and the chimney.  The chimney would allow
air flow between the pipe and the fiberglass top to keep things cool.  I
think they're called "stove jacks", an inner and outer sheet metal
arrangement with air holes at the top.  These could be closed off when
not in use.

The whole thing would be made to fit over either one or two burners,
the decision there being whether to leave a burner available for cooking
whilst using one for heat.

A thermostat would be needed to determine 1) when to turn the fan on/off
and 2) as a safety mechanism to somehow shut off the flow of propane in
case the propane flame blew out due to high winds.  You think carbon
monoxide is lethal, try an atmosphere of straight propane.

Anyway, that's what I think about this whole thing.  Everything (believe
it or not, to those that are mechanically challenged) is fairly straight
forward, except for the propane cut-off, since a 12V solenoid would have
to be sandwiched into the piping to the burners.

So what do you think?

Jack
jackr@starfleet.scs.ag.gov