you would be better off using all tanks inside your camper van especially during cold weather months. as long as you keep the van heated nothing will freeze i use 2-5gallon under sink water jugs one for fresh water one for gray water with a water pump to the sink, very easy to use and dump. and a Portable Toilet that is easy to use and dump in any toilet like this
Portable Toilet this all works great for me and has down to a -38 degree night (i have a 20,000 btu suburban lp gas furnace also). there are hundreds of ways to do it and a quick google search can find them like this
Fresh and Grey Water Tanks
