Hi! I recently bought a 2005 GWV dodge sprinter 2500 and had to reconnect the kitchen sink piping. The hot and cold 1/2" PEX come up thru the floor just above the propane tank and the previous owner had cut them off about 2" above the floor when replacing the fresh water tank. Thanks for that! Anyway I believe the pipes just run over the top of the propane tank and through a steel radius-preserving holder. This prevents the hose from kinking as it goes around a corner. It is very difficult to get at the pipes without dropping the tank (which I did not want to do!) Thank goodness I was able to use a 1/2" PEX sharkbite connector above the floor to connect to the old and new pipes. Instead of dropping the tank I was prepared to just feed new pipe from the top over the propane tank and connect with a sharkbite to save having to remove the tank. I couldn't see any "fittings" above the tank itself. I'm not sure if this helps but it may provide an alternate solution for you.
Cheers,
Mark