So, based on the feedback so far, I am going to get some clarification again on mixing 6V and 12V batteries. I thought it was a big no no as well, but the dealer is swearing that this is the way to go. Their extended warranty will cover all of it from day 1. Their selling point was this is peace of mind and no matter what happens, you are covered.
But, I am skeptical on this setup as well. The CS I am buying has all the E-Trek - solar, engine gen, 3500w inverter. I am going to call them out tomorrow and if I am not convinced, I am going to tell them to lose the 6v batteries in the hood.
All the feedback is helpful, but I still want to overbuild this. Sorry. You all should see my home electronic / computer setup. It is just as ridiculous.