We have a 16' UHaul
trailer that we pulled from Chicago out to Rocky Mountain National Park and back last summer. The UHaul
has a double-shell wall structure for some added insulation and is totally smooth fiberglass
inside (no rat fur). We get a bit of condensation on the windows
when it gets down close to 32 degrees and the furnace
is running, but we keep the bathroom ceiling vent open and have a fresh air source under the furnace
. The better the ventilation, the less the condensation. We haven't had any problems with condensation on the walls yet.
We run our furnace only for about an hour a day (getting ready for bed) and use a small ceramic electric heater other times. We also cook with our propane
stove inside when the weather is not nice outside. Thus far, we have used about 1/3 of a 20 lb. tank since it was filled in spring 2007. Of course, we are not running the furnace 24/7 like you asked.
We are towing with a 2003 VW Eurovan with a V6 engine and get about 14-15 mpg on trips west. We get a bit better mileage going east (downhill!). We don't have a special hitch, just the regular 2" ball.
As to handling, we have had no trouble, even in very strong winds in South Dakota. Of course, any wind can catch you just right and cause some problems, but we just slow down and drive consistently around 55 at those times. Otherwise, we go 65 mph on the 4-lanes. Trucks passing us have been no problem at all. In fact, I honestly haven't noticed any effect from their wind. Our trailer runs about 2500 lbs loaded, so it's pretty stable.