I don't understand the description of the cord from RV to cabin. Two male ends?
Anyway, you don't need an RV for the job as such. You can rig up a utility trailer that you could tow with your car. You will be in the cabin not the RV?
The utility trailer could have a portable generator, batteries, an inverter, and some gas cans. The cabin solar can recharge the utility trailer batteries as required. Take it all back home between visits and no worries about theft.
AGMs are good for the cabin job since they have a low self-discharge rate when left disconnected (so disconnect them :) )
