I have a Multiplus 3000 and a Victron Orion B2B. I am running a Nations 280 amp charger setup for AGM batteries, shore power, and no solar. I'm confused about what I need to monitor and control the inverter. Do I need the BMV712? Should I use a Cerbo GX and Touch 50? Will that do what the 712 would do or do I still need that. Will that give me everything I need? Do I need to purchase a shunt too? HELP! I have a guy who will be doing all this but I don't think he's familiar with all the Victron options.