Cee:
Cool, we will have to be careful waving at each other when we pass on narrow roads!
We decided 2 days ago to go with a 24V system. It makes so much more sense. For powering the 12V furnace fan, water heater control, led lights, and random 12V accessories, I am going to either use a 24V to 12V DC-DC or I will use a battery equalizer like the Vanner 65-60 (which sort of bank switches between the series connected batteries and gives you 12V). The Vanner is about 2x the price of an equivalent amperage DC-DC. We are definitely going with the Magnum 24V input 4000 watt output hybrid inverter with 125 amp battery charger and generator sharing capability. Total overkill but +1 on cool factor.
I built my own LED fixtures by hacking home LED lighting, tossing the electronics, and putting in potted DC-DC converters. They work extremely well and I have set the current draw and light level exactly where I want.
The walls are 2 inches thick, with polyisocyanurate insulation (exact stuff you used). We have had the windows on hand for months...we had them custom made by easyrvwindows (Atwood mobile products). Double pane, openable..pretty nice and not too expensive.
