four season 5r's
Jim,
I live full time in my 30.5 foot,1995 Prowler 5th wheel. I live very comfortable and have never had a problem with cold weather.
I just had my propane tank filled a few minutes ago and It figures out to $1.17 per day for the furnace, water heater and cooking.
Here in northern Nevada the temps for the past month have been in the teens at night and mid to upper 40's during the day. We have had a couple of snow storms also.
The Prowler is the best all around rig I have ever owned and I've owned several over the past 40 or so years.
In my opinion,, unless you live in the extreme northern areas of some canadian border states of America like Minnesota or North Dakota and plan to never leave that area,, I would just buy the RV I want and don't worry about any special package designed for the winter.
You said that you would be traveling all over America and staying here and there for 3 to 6 months. That means variety and fun.
Simply by using a little common sense, you will have no problems.
One thing I would suggest is get a 5th wheel that has at least one SLIDE OUT..
You'll be miserable without it, and the resale/trade in value is MUCH GREATER than a trailer without a slide.
Best wishes on whatever you decide on,
John