Agree that there is no need for major panic. Most years we've waited until Thanksgiving to winterize and have had some overnights in the range you're looking at. We used electric heaters and opened cabinet doors. It's only going to be that low for a few hours and then warm back up...the term "warm" loosely used. Closing the slide will give you less area to have to heat, but if your furnace normally keeps things comfy, wouldn't worry about it. Either way is fine. Disconnect the water hose and drain it. You might check to see if your CG has freeze proof faucets and if not, what their plans are.
Guess you could disconnect the slinky, but have no idea what the thinking is behind that. Really do not think you're going to have any problems. Do they even SELL RV Antifreeze in that part of the country??
We're a toasty 33 right now - up from 16 - but the bottom is due to fall out - again - this afternoon. If it's going to be this blasted cold, might as well have some snow and really shut the place down. DH agreed to make a dog food run for me....he's not gonna be happy having to drive near Walmart to get to Petsmart, but doesn't realize that yet. Won't be a loaf of bread or a gallon of milk to be had....people!, this is not gonna last forever! Better if you can just enjoy this time of being closed in, grab a good book, watch yet another bowl game or make homemade bread. We'll be back to the real world before long.