Two Additional Comments.... First, NBB your a genius!!!!
Just got done planning with a friend of mine (who used to run maintenance in large hotels so he is a plumber extraordinaire!) how we can break into the water system just past the water heater, run through a recirculating pump (not the standard pressure based pump) connected to a thermostat in the fresh water tank, and run a recirculation system to keep the water at 45 degrees F. We plan to work it in the next month... as winter has a long way to go and to Live the Dream... you have to be ready to go at a minutes notice... in winter or any other season...
Second comment, Hit the Road Jack suggested putting your tanks within the van.... with good planning you can find space for them I would guess, but I would caution for a couple of reasons. The water tanks should be over or behind the rear axle for stability and weight on the springs for ride comfort. Second is the premium of space. Having had a 2500 Sprinter B Class RV the space premium for having the tanks within may not be worth it, especially if you design for external tanks used in winter. My 2500 B had the fresh water inside in the sink podium...unfortunately that was in the middle of the van at the sliding door so the weight there made us less stable and the rear more bouncy, my grey and black were external... but pouring antifreeze down the drains and toilet took care of those issues in the cold. So at worst, only put the fresh inside...
Again, this forum is a great source of knowledge, ideas and challenges to make me think about options... Thank you...
LivingtheDream
Turn the Key and Smile
2009 LTV Freedom II Freightliner 3500