Item location on the tongue

I have a 179 - 2015 model.  I have two 6v GC batteries that are mounted up against the curve of the front of the body, making it very difficult to check water etc on the batteries and easily remove them for winter if wanted.  They reside in a plastic box with lift off lid that came from the dealer when I bought the rig new, which is difficult to access and marginally secure.  I want to put the batteries in a Harbor Freight box with a hinged lid, but would have to set the box forward about 6" to allow the lid to open without scrapping the body.  I have been working on this project since March and we have not been camping so there is no urgency. I have plenty of battery cable.  I came up with the idea of putting the propane cylinder back where the batteries are now since the propane cylinder has a recessed top valve, and attaching the new battery  box where the cylinder sits now.   I previously added a Jack-E-Up mount to the Trailer jack, and the box would b e a convenient place to store the jack when traveling.  I have the limited welding capability and scrap steel. The propane pressure regulator could attach to the new box somewhere.