First, thanks to Terry Jay for the links. The Escapees forum is interesting - have spent several hours reading already.
New Horizons: heavy and large certainly describes! I thought Mobile Suites was the heavyweight, but New Horizons appears to be very heavy. Their website shows that the shortest fifth wheel they make is just shy of 37 feet and then going on out to 46 feet or so. I notice a number of the folks on the Escapees forum have New Horizons fifth wheels which they tow with HD class tractors. Apparently there is a whole cottage industry in converting used HD tractor trucks into RV towing rigs. The argument for the converted HD tractor is: more than enough power to go and far more power to stop; comfortable ride; fuel economy is as good as smaller trucks when towing; cost when purchased used is highly competitive; since truck originally intended to run for a million miles, purchasing with 300K to 400K miles means the truck will outlive the purchaser when used for full-time RV. I don't know enough to assess the accuracy of all of that, but there are some true believers.
It occurs to me there is such a thing as too many choices. There is a very wide variety of how people approach the whole RV thing. Thus, I think the first thing one needs to do is decide what type of travel you envision. My greatest desire is to go to the places that I can get close to nature; hence, I think of state parks, county parks, national forest, national park. There is a large variety, but I think I'd like to stay in the 34 ft to 36 ft range (motorhome or fifth wheel). That narrows the scope just a little, although there are still multiple options.
Good thing I have years - looks like it will take that long to absorb all the information!
Looking forward to hearing more.