There are gas (!) stations here in Colorado that
sell LPG.  There are fleets of vehicles around here
that use it.  I don't think they have to park them
inside....  They are mostly trucks, so the big tank
isn't an issue.

I remember thinking carefully about converting my
'67 splitty to dual fuel in the oil crisis of '72.
There were kits/parts available then to do it pretty
simply.  You could switch from gasoline to LP and
back without any trouble.  Of course, those were the
days of carburators, but the AFC vane should do
the same thing as the butterfly in the carburator,
which was what the LP system keyed off of.

If you find solutions, please post them so we'll all
be up-to-date.

                        Richard A Jones
                        Boulder, Colorado