Mark: You are definitely going about this the right way and will avoid a nasty $$$$ pit fall later. So many of us have gone down this road before you and made the mistake of wishing those lower "unloaded vehicle weights" were the holy grail! Some manufacturer's don't even include the additional weight of Gel-Coat (approx 13Lb per running foot) fiberglass in those UVW's and they haven't made an aluminum sided or Filon fiver in years.

Sure a lot of good information on this thread and I just purchased an 08 Chev Dually for my 06 Montana 29RL, Montana's smallest model. This 5th wheel is 33 feet long and when loaded up puts 2600 pounds on the pin.
The only SRW 1 ton that will legally pull my trailer, the way I load it, is the Ford because they have the highest payload. I decided I wanted to try a Chev this time so I had no choice but to go to a dually 3500 with the 11400 pound GVWR. This truck has an almost identical payload as my 05
Ford F350 V10 which was an 11200 GVWR ( PSD trucks in my model are 11400 ) My Chev Dmax weighs about 200 pounds more than my Ford V10 did so payloads are the same.
In the Montana Owners Forum, the most active posters convince newbies that a 2500 HD Duramax with a 9200 LB GVWR is all the truck you need for every model that Montana makes. Complete hogwash!
Disagree with them and get punted off the site like I did. Great to belong to an RV forum with people that know the facts and practice them.