I found this whilst looking for a good electrical system for the batteries this might solve the 3 battery question for you
SC80PCWK_Info
I am thinking of this path so I can put a large battery, maybe two in an off-road trailer with a solar panel as well. My concern is the alternator will I need to upgrade? or can I get the existing recon'd and retrofitted to give me a greater output, had this done to my Toyota (sorry for swearing) which worked well but that was back in the early 90's.

