battery switch

Hey all, New to forum with my purchase of a 2017 Benny. Love the boat and quality. Already adding a 2nd battery with a blue sea ACR (mini). When finished, adding a sub and amp along with a on board battery charger. My question is the grounding of the ACR. I have the current ground from my...

Poor quality scan of my original diagram but this should give you a basic idea of how I connected everything. I tried to note on the diagram the wire gauges I used and the size lugs that needed to be on each individual cable. Used 4 AWG everywhere except from the ACR to the both batteries -...