Thank you all for the advice replies in my post last year:
Remember, I used the Roadtrek all winter. So here is what I did.
I plug in along side of the house so I got a Pelonis ceramic heater and put it on top of the stove. I felt that area was designed for heat anyway. The heater thermostat was adjusted to keep it just over 50 degrees and I checked it on the coldest days. I drained the water heater and set the valves to bypass. I winterized the tanks the proper way but then I added 4 gallons of antifreeze to the lower tank. This lasted all winter to flush the toilet with as suggested. I carried a two gallon jug of fresh water and this was enough for my day trips and a few winter overnighters. I thought I would fill the inside tank for my winter camping trips but the two gallon jug did the trick. Anyway, I used it for day trips all winter, two winter camping trips and as a spare bedroom over the holidays. Now my tanks are flushed and sanitized and I replaced the anode in the water heater and yes, I ran Onan the Barbarian regularly...