1 Solar Monitor-Marine Switch-2 Batt Banks on RV!

[aztecaa]

Thanks for having this forum to help others. Noob here and need some advice on EXISTING setup! I just bought 4 large Marine Deep Cycle batteries (12 volt ea) used from a sail boat setup and i don't want to connect them to my existing bank of 8 (6 Volt deep cycle batts) all together! From what I read, don't mix old with new, one batt that is weak can drain them all down to it's level. I'm adding a new battery bank separate from the first battery bank using a Marine Isolator switching from one to the other but Solar Charging both banks at the same time or separately, from the Solar Monitor! Or Going directly from the Solar Monitor to the Marine switch and and manually switching from one batt bank to the other for charging purposes. My setup: 1 battery bank of 8 (6 volt deep cycle batteries) which includes the 2 bay. Solar-monitor-battery bank-inverter! ON a RV, which I'm living in while building a house above it. My RV runs on 12 volts and my true sine wave inverter is also 12 volts in. I wired up the 2nd bank of 12 volt Marine Deep Cycle batts in parallel and NOT sure how to tie them into the Marine Switch along with the Solar Monitor and then out to the Inverter. Do I need another switch for the Inverter! Thanks for any and all help with a DIAGRAM!