Just curious......if generator prep didn't include battery cables what did the 'prep' include?
Generator prep on our 5vr included a metal insulated box in side compartment with battery cables, remote control/monitor cables, cut-out for exhaust and transfer switch wired in.
As posted.....generator starting battery is good but would still need to be connected to trailer battery/converter to maintain charge.
I'd just run battery cables to generator compartment.
Remove screws in underbelly along frame edge and route cables.