I'm in the same boat. We're just out of Houston. I've only half heartedly winterized before. I think I will just drain the water heater and the tanks. Pour a little RV antifreeze in the drains. I'll stretch a good extension cord to the 5th and turn the furnace on low. Let me see if I can get a link to the Landmark winterizing procedure to post here.
https://manuals.heartlandowners.org/manuals/User%20Guides/Winterization%20Guide%20V1.2.pdf
There should be a drain for the icemaker under the trailer just under the fridge. My icemaker supply comes from under the sink.
The Bigfoot I'll do the same except maybe no furnace on.
Wish the weather people would make up their minds. Forecasts have swung from 5F to 36F overnight. Looking like low to mid 20's now.
I have camped in both the RV's down to mid teens with no issues. Fingers crossed.
Maybe better link: http://manuals.heartlandowners.org