Using rv during travel out of cold climate

old guy wrote:
unplug the rig from the truck leave rig hitched up and go to bed

Reminds me of a (relevant?) story. We stopped in the Mount Pleasant TX Walmart where it went down to 20 overnight. I woke up in the middle of the night quite cold. Furnace was blowing very cold air. Enough power from the single battery in the RV to run the fan but not ignite the furnace. Not enough to start the generator. So I went outside and plugged in the truck which had enough juice to start because it was unplugged. After 20 minutes there was enough recharge to start the generator. 5 minutes later, the furnace lit up. I went out and unplugged the truck again. After an hour, I shut off the generator and was toasty warm for the rest of the night. Said to DW the next morning "Wasn't that a nasty problem with the furnace, the truck and the generator last night". She said "What problem?". I guess I'm more sensitive.

Anyway, don't leave your truck plugged in - you don't want to run your starting battery flat!

(I have 2 batteries now).