Sounds like you may have the same tongue situation I do.
came with 12 volt (when plugged into TV) but no battery, propane
supports are too close to trailer to add a battery behind it AND if one moves the propane forward (trailer shop said about $50) then the crank handle for the jack mounted on the side of the tongue would hit the propane tank. Because crank handle rotates horizontally
I figure I have two choices if I want to move the propane tank forward enough to put a battery on the tongue.
Replace the hitch with a modern style that has the jack mounted through a metal plate that is part of the hitch. Then purchase a jack with a vertical crank. Advantage to this is max room on tongue and I can change hitch to be for a 2 inch ball rather than the old stock 1 7/8 inch. Don't recall the price but it was obviously more money for more welding and the parts.
Or I could jus have them move the tank, then cut the crank handle a little shorter so it does not hit the tank, drill a new hole in the crank arm and move the handle, less leverage but it does not take much to crank up a Scamp
13 eh? Advantage is I get my battery tray and am probably only out $50 for the work of moving the tank and adding a couple of angle iron pieces for the battery.