I'm installing a 30 amp Victron DC to DC isolatedcharger for my RV trailer to charge trailer Lithium battery bank. Have 7 Pin charging but not sufficient for a trailer Lithium battery bank. Vehicle is 2019 Suburban LS with tow package. Suburban wiring is fused positive wire (4 AWG) off Suburban battery and negative ground (4 AWG) back. Both wires terminate at an Anderson Connector at rear of Suburban for connection to trailer that has the DC to DC charger installed. Is there an easy ground point at back of Suburban that could be used so ground wire does not need to run back to a front ground point? It is long run and having a short ground run would easier. Frame seems obvious point but not certain it is sufficient. thanks for any input

Charger wiring diagram

 

I would use the frame on the truck for a ground. Frame is the common ground point for the truck. Most of the trucks neg. wires connect to the frame at multiple points.
If that charger needs that much power, then it will overload the trucks alternator.