Black tank, Start by adding a quart of pink RV antifreeze, this will get down in the valve area and more or less protect it.. Then carry jugs of water (Like perhaps 5 gallon) inside the motor home.
As for de-winterizign on the road. Two options.
FIrst: you can sanatize then blow out the lines now... This way you need only do the final fill (Sanatize run, soda run, rinse run)
Option 2 (how I did it) it is legal to dump fresh water, and both your bleach and soda water everywhere.. You may, nowever, have to prove it's clear water not waste.
I filled with water and bleach, then drained, filled again with water and baking soda and drained, then filled with fresh and drained, finally filled at one of my stops... NOTE: after you fill you run the water 1: Bleach 2: Soda 3: just water through all the lines of course. Never had a problem doing it this way. No complaints. if you are in a parking lot not a campground (Best to be in a campground) you park so the fresh tank drains into a drain.
