We've had our FR3 32DS for going on three years. We've taken 1500+ mile trips in weather that has been cold, wet, hot and dry. From my experience, the furnace handles cold weather just fine. I've never been cold and we've been in weather right at the freezing mark with strong winds. If there's an issue, it's with really hot weather. The older models' AC couldn't handle much over 90 or 95 degrees. The newer models have a more robust AC unit, so that's either been fixed or improved.
When traveling, we've had people over (not over night). We always have to use both the dinette and the couch, but it seems to work. We don't turn the captains (driving) chairs around, but that's always an option.
I've been on this site since the time we purchased the coach. Several people have taken extended trips (thousands of miles and months at at time) and seem to do well. I don't know if I'd want to be in it more than three or four weeks at a time, but that's me. Our conditions are like yours; two of us and two small dogs.
Good luck with your decision.
Jay & Jane (Jazzy and Jewel, too)
2014 FR3 30DS
Twin Cities, MN