My inverter peaks at 5KW, so I need a large battery bank AND alternator to power it, more than the present alternator and battery can handle.

This machine already has 3 power systems on board; a 12VDC engine and running gear system, a 12VDC "house" system and a 120VAC "house" system for shore power or generator.

Separate systems will allow the most flexibility. A few brackets and minimal wiring, and it is done.