Glenn: I use air to blow the black tank flush out first (drain valve open) than I use a hand pump to add "some" pink to the tank system. Don't want to take any chance that some water may be trapped and freeze. I'm more concerned with our 5th wheel that sits on a lot year round (no movement) than the MH which has lots of movement. I still do both each year the same way. So far, TG, we have had no problems with freezing water lines in any of our RV's doing this proccess. Over kill maybe, but where water goes it's blown out and PINKED.
2 of us + 1 rescue, Sadie (not sure who rescued who)
Toad: 11' 2dr Jeep Wrangler, 2010 Fit Sport
11' Bay Star 3302,11' Alpine 3555RL 40' 5er