Your on the proper track. Everything you said you are using for hardware is fine. I also used 6awg wire. I did use the fuseless switch style circuit breakers which also work well as shutoffs when necessary. I have one 50amp on the truck side and another on the DC to DC charger side.
T Tocas Hi-AMP T3 Circuit Breaker...
https://www.amazon.com/dp/B01F76VJKQ?ref=ppx_pop_mob_ap_share
Set the Victron DC to DC charger in standard alternator mode. Your setting for battery type depends on the batteries your using in your RV. I'm running 500ah of Battleborn Batteries in my setup so I set voltage parameters on the Victron app for lithium accordingly. Battleborn provided me with the settings for input into the app. Pretty straight forward but has to be done correctly so you get the maximum performance out of the batteries. Same also goes with the solar controller.