Here is an update on my battery box mod. Unfortunately I could not complete this mod. All the measurements I took would appear this mod was the ticket. The only way this mod would have worked was if I moved the propane tanks tight against the power tongue Jack. Doing this I found the propane hose from the regulator to the TT was short by 9 inches.
Yes I could get a new hose but I found other issues.
The lid on the box was also too tight against the front of the TT only allowing it to open only 1/2 way. Bottom line is I am lacking the real estate to do this on the A-Frame.
I ended up ordering the B&D RV Battery lock others have mentioned here. I'll find something later on that will fit
2015 Jayco 24FBS Elite Jay Flight
2013 Chevrolet Silverado 2500HD 4X4 6.0L 3.73 Axle
HD Trailering Package with Integrated Brake Controller
Equal-i-zer Hitch 10k/1000