[BB_TX]

Assuming yours is similar to my Montana (not Mountaineer) and you have a Winterize connection in the convenience center, here is what I do when winterizing.
Start the fresh water tank draining.
Bypass water heater, remove anode rod to drain it.
Turn winterize switch to winterize position.
Pour 4 gallons of antifreeze in a bucket.
Connect a short hose to the winterize connection and drop the other end in the bucket. (I have a hose about 4’ long and set the bucket on step ladder near winterize connection).
Start water pump.
Open one low point drain valve until I see pink stuff and then close valve.
Repeat with other low point drain.
Open outside shower cold valve until I see pink from the hose.
Repeat with hot valve.
Connect outside shower hose to black tank flush connection in convenience center, open one shower valve for 10-15 seconds, then close. (My shower hose has a standard hose fitting, not s spray head)
Go inside and open the kitchen faucet cold valve until I see pink, then close.
Repeat with hot.
Repeat with bathroom faucet and shower.
Hold toilet flush until I see pink, then release.
For clothes washer I set water temp to cold, run washer until I see pink, stop washer, start spin cycle to drain.
Set washer water temp to hot and repeat.
If you don’t have a washer but do have washer connections you need to winterize those lines.
Turn winterize switch back to normal.
4 gallons is typically enough but I am generous with antifreeze do I buy 5 gallons.

Since mine stays plugged in to power in storage so I leave the battery in place and just check water lever periodically.

Your connections and switches may or may not be the same.