I have had the NH for the past 5 months - so I'm still finding out new things to watch out for. My install was also a modification from the norm in that we pipe the urine back into the black tank, which is merged with the gray for a total capacity of 65 gallons. Hence I don't have to deal with a 2-gallon bottle of urine every 2 days or so.
The fresh water supply (55gallons) last a lot longer as none of it is being used to flush the waste. I carry a couple of 5-gallon plastic jugs which I fill with fresh water whenever I find a spigot of potable water. Using a 4-foot aluminum step ladder, I perch a full 5-gallon jug on top of the ladder, then attach a short hose from the jug into the fresh water fill and let gravity do its job.
1987 Excella 32-foot
1999 Dodge Ram 2500HD Diesel