Our prior tow vehicle was a 2003 F-150 5.4L. 12-13mpg non towing, 15-16mpg highway, 6.5-8mpg towing the same TT. I wanted to replace it with an Ecoboost F-150, but my wife wanted 3 rows of seats. Of course she won! If Ford offered the same Ecoboost in 2012 Expy, we'd probably have that instead. The half ton Burb wasn't enough of upgrade in performance and payload from what we had. The 3/4 ton up front costs are dirt cheap, like less than $1000 for the same equipment on a half ton. In fact, the 20" wheels on the half ton cost more than $1000! Obviously, there are other compromises in now towing ride/handling and fuel.
We have taken our Suburban on a few non towing trips. 2650 miles Michigan to Orlando and back wasn't great, winter time, high speeds, and not broken in engine. We got 16mpg down, 14mpg back. At 20k miles we took a trip 1000 mile in warmer weather, averaged 17.7mpg. One camping trip we took a long day trip from campsite to Michigan's Northern Peninsula and got 20mpg over 250 miles, but at double nickle speeds. Last Christmas we drove to South Carolina about 2000 miles round trip and got 17mpg. Speed and weather conditions vary, but just as I expected, about 1mpg lower than ktosv in all conditions. 13mpg winter, 14mpg summmer, 17-18mpg highway, 8mpg towing at 65-70mph. I am really impressed with the 6.0L and 6-spd combination of power/capability and fuel usage. The 3/4 ton Suburban (maybe vans too) have EPA fuel economy ratings so my Monroney sticker said 10 city, 15mpg highway. This is one of the rare vehicles that we exceed the EPA ratings, and by a fair amount.
G80 locker is something I recommend. It is inexpensive option new and very effective and durable. It is very common (about 80% production rate) on the SUVs and pickups, but I'm not sure the vans. As you shop specific vehicles, GM makes the options fairly easy to determine. There is a sticker in the glove box with a list of RPOs. G80 would be the RPO code for the locker. All the other RPOs can be searched on the internet. Plenty of GM RPO decoder web sites.
Before we bought the new Suburban, I was looking for used 2004-2006 8.1L models. I found
this site extremely helpful due to my "special needs" AKA very specific option requirements. The reports used to be free for 5 per day, but very interesting statistics on number built per year for specific options. Anyway, might be worth $25 as you shop.
2010+ with the 6.0L/6-spd only. There are 4.8L in 3/4 and 1-ton vans mated to a 4-spd trans. Don't bother with them. Not built for RV towing IMHO. And as you say, you'll pay a lot less for the van than a less capable SUV!
A & A parents of DD 2005, DS1 2007, DS2 2009
2011 Suburban 2500 6.0L 3.73 pulling 2011 Heartland North Trail 28BRS
2017 Subaru Outback 3.6R
2x 2023 Chevrolet Bolt EUV (Gray and Black Twins)