I saw a pic of a home-made TC with a propane cylinder strapped to the back of the camper.
If I had a physical/ medical need to move the propane to someplace more accessible, I'd look into plumbing the lines down to a hitch-hauler tray and build something to house the bottles there... even if that was just a ratcheting tie-down strap.
To avoid having to do fancy plumbing mods, you could just get an extension hose and leave it coiled up in the original compartment. When setting up camp, pull the end out and hook it up to the tank on the hitch-hauler. A pain, no doubt, and precludes propane fridge use while driving, but very cheap and easy to implement.
HTH