With an 83 gallon motor fuel tank I elected to plumb a POL to 1/4" stainless steel braid motor fuel grade hose (using a service loop) to a red ten pound regulator with tap (Barbecue Tiki torches, etc.) then a full size million BTU gray reg. Both are mounted on the chassis.
Since all the parts were free, I then used schedule 80 black iron pipe port and starboard chassis frame rails. Up through the 11 gauge steel floor, to low pressure steel braid hose, then an LPG **** valve that is accessible.
Why did I do this? A few 100+ mile trips to the butane plant down here made a believer out of me. I have schedule 80 plastic pipe buried next to the bus that feeds stove, a pizza size oven and a Bosch demand hot water heater for shower and dish washing.
The LPG system was installed by a friend (we traded work). The work was done I believe in 1988 on the bus. I have had zero problems in 30 years and the secondary reg still maintains 11.0 inches of water column on a manometer.
New LPG project
Find a 2 foot square piece of 3/8" aluminum for use with two small burners as a hotcake griddle. With frying pans or cheap griddles when batter is poured onto the griddle the temperature sags and that royally screws up the hotcake. My propane guy taught me this. If you use IHOP flour, you will end up with perfect IHOP golden hotcakes. It is the secret to making perfect hotcakes.
Anyway my "luck" with different brand small regulators is sad to behold. I got tired of screwing around.
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ROOSTER