I had a dealer install a locking metal battery box to hold my 2 GC-2 batteries on my A-frame. Actually, all I wanted was a plastic box without a lock, but he ended up sourcing this metal box. It cost him about $230, I believe. He didn't charge me, because I was going to do 2 single plastic battery boxes without locks for about $20 each. I cut holes in the end of the metal box and mounted a marine battery cut-off switch.
2019 Flagstaff T21TBHW A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time