Not too hard to do
I'm just 40 miles from you and here's what I have been doing for the last 10 years. My trailer is in storage east of Dripping Springs.
I open the 3 bottom drains and let the lines and the fresh tank drain. In the mean time, I pull the plug on the water heater and let it drain. Then I replace the plug, close the bottom drains, and blow out the lines by opening one faucet at a time. Don't forget the shower. In Classics, open the outside faucet, as well.
When all lines are clear, pour a generous amount of the pink RV antifreeze in each sink trap and in the shower trap. The shower trap is the most critical since it would be a bear to replace if it cracked.
I disconnect the input to the water pump and shake the water out of the filter. Then I run the pump for a few seconds. To disconnect the input, press in and turn. There are plastic "wings" to make it easy to grasp the input. You should clean and inspect the filter once in a while, anyway, so this accomplishes that.
I don't disconnect my batteries, but I would recharge them periodically. If you can't recharge them once in a while, then remove them and store them in a warmer place.
All this takes me less than 1/2 hour. I have never had a freeze problem. My trailer has AC power in storage . I leave the heat pump on and set to 40 degrees in my Classic but power could always go off in an ice storm.
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"