We recommend to install a nominal 24V solar charge maximizer controller, LiFePo4 Battery Bank, and off-grid inverter solar power system with automatic transfer switch, and leave the original 12V lead /acid  battery outside the recreational vehicle. The LiFePo4 battery shall be located inside the RV to prevent freezing while charging. The hybrid solar power system will power the RV as if you have shore power all the time for unlimited boon-docking time.  

In the recreational vehicle and boat application, the LiFePo4 (Lithium Iron Phosphate) battery must be located in the battery compartment with temperature control. Because LiFePo4 battery will stop charging when the battery temperature falls below freezing point.

The distance between recreational vehicle and the solar panels in parallel connecting solar charge maximizing controller is limited. The SCM controller is very beneficial to the recreation vehicle applications. In case of LiFePo4 solar energy storage battery, the MPPT solar charge controller may even be waived, since the wiring cable distance is no longer an issue.