I leave all faucets OPEN after blowing out. Drape the shower heads lower than the water source, also open, pour pink stuff into all drains (one gallon total).
After draining the water heater tank, I loosely put the plug back in, even though I know that the aluminum tank can handle freezing the tiny amount of leftover water easily. Just habit.
On the freshwater tank, I open the gravity drains while I'm winterizing and close when I'm done. I do remove and drain the water pump, the plastic connectors are only finger tight. Takes just a minute. Then I leave it in the water bay. And I close up any openings in the water and waste bays.
All the holding tanks, since what little liquid remaining is spread all over the bottom when empty, really not a worry. Even if that small amount of water freezes, it won't damage the tanks. Also, they're vented to the roof. The holding tank valves are left closed over the winter.
I spent three winters in Fairbanks, Alaska with it's -40F days and -55F nights for weeks and weeks, without problems using the blowout method. Coldest I heard of while I was there was -70F for several nights.
In spring, back living in the RV within a hour of hooking up.