Hi JJ,
I routinely use my RV at -17 F and have used it at -35 F. I usually have only 1 15 amp connection which I must share with my block heater (or my diesel won't start), and I don't often have access to the breaker panel if I happened to "trip it", so I balance my "load" very carefully.
Start by cutting down the area that is being warmed. A nice thick blanket across the Cab area works well, and a blanket over the door can help too. I sometimes cover my windows and have some foam "inserts" for my roof vents.
At night I have a safe place to put my heater in the bedroom area. I close the curtain which again reduces the area being heated.
Look for a radiant heater--I found a grand one at Walmart in December--it has made my life much nicer in the RV. Do a search on this board for radiant and the url to see it may turn up.
The nicest item I have for cold weather boondocking is a 12 volt electric blanket. I'd really rather it were a mattress pad--but I've not found one that is 12 volts yet.
I run my furnace extremely sparingly--but do cycle it to keep my waste tanks warm. I wish I could find a way to run the furnace fan without the burner being on--that would keep my tanks toasty warm, and warm up the floors too, while I'm actually driving down the road.
I do use a carbon monoxide monitor when I am boondocking.
I don't use my water heater. For washing I heat water on either an electric hotplate or the stove. Last year I rewinterized 6 times!
I have a nice long #12 cord so if there is a "2nd" outlet on a different breaker, I'll use that for the block heater--or in really extreme weather the block heater and an additional small electric heater in the tanks area.
I also carry a 2800 watt generator "just in case" the power goes off on me.
QUOTE(DXSMac @ Mar 20 2008, 12:20 PM)

Tomorrow, I will start a two day "extreme boondocking" experience. Yesterday, I arrived at my sis's house in Eastern WA, where the lows are still 28 degrees at night. I'm on a 20 amp connection, so I could only run ONE space heater. (I try not to run my furnace until it's abso-freaking-lutely necessary.... want to save the propane....) It was a little chilly last night, my thermometer shows it was 46 inside my coach despite one space heater.
Tomorrow, I'll be headed to Idaho where we are having my Mom's 80th birthday for the weekend. (
http://myidaholodge.com/ ) I'm going to be the only one "boondocking" in the parking lot in my RV. Weather predicted highs in the 40's lows in the high 20's. And no, I'm not going to chicken out by taking a room in the lodge, after all, my cat is with me, and I will stay in the RV with my cat.
For me, this will be extreme boondocking for two days. Any hints? And what has been your most "extreme" boondocking?
JJ