You'll be very comfortable.
We've had our 2011 Rushmore in the Colorado mountains twice for extended ski trips. Last year temps were below zero (F) almost nightly and as low as -30 one night, -20 two nights. We run the thermostat at 74 to keep the underbelly warm. We also have the fireplace option which keeps the back end warm. We also have dual pane windows. No matter how much the furnace runs, the water line to the kitchen can still freeze when it gets to about -15. The water line to the bathroom freezes at -20. Temps in the low teens should not be a problem.
The Yeti package will give you tank heaters (which we have) and heat tape on the main water line (which we don't have - not sure if that's the main from the fresh tank, or something else).
Our biggest problem below zero is the gate valves on the tanks. We use a 3" heated/insulated sewer pipe and keep the gray tanks open (so we don't have to deal with those valves until we dump the black tank. I plan to dump the tank every 6 days and watch the temperature forecast to dump on warmer days. That way the valves have defrosted even if they did freeze. In the low teens I wouldn't expect valves to freeze.
I run a 100W heat lamp behind the basement wall, pointed at the water pump and plumbing lines. I run a 60W drop light in the UDC to keep the incoming water lines warm. And of course the city water hose is heated and insulated. I tried a Pirit Heated Hose but it quit after a few weeks. The replacement worked for a few weeks last year and a few days this season, then it failed. Instead of another, I added heat tape and insulation to the failed hose.
We don't have a skirt.
If you'll be in one place for a while, get a 100# or larger external LP tank and have the LP company make you a hose with overpressure shutoff so it doesn't damage your regulator. Keep one of your 40# tanks full, in reserve so you always have a fallback at 3AM.
Another thing: there was a storm this season that knocked power out for about 8 hours. The furnace draws a lot of power - you'll run your battery down pretty quick. We have 2 batteries and ran for a couple of hours on battery, then fired up the LP Generator for a couple of hours to recharge the batteries, fire up the tank heaters, and turn on the basement/UDC lamps, and heat tape on hose and sewer lines. Without the generator, we might have had some frozen lines and a cold coach.