I was under the impression that the propane was not to be used while the
van is being driven unless you want to make it "the toast of the town."
Use the 12VDC for transport mode.  I believe I read several horror stories
on the Westfalia Owner's Website.  Cool it down with 120V AC, go to 12V DC
once underway and only use propane at the campsite.
                                                        Jay