Most modern SUVs are set up with very soft springs and P (passenger) tires because people want a good ride. An Escalade probably has a payload rating of around 1,500 pounds. Your 8,000 pound RV will have a tongue weight of probably 1,200. Your weight distributing hitch will add about 100 pounds. This leaves very little extra payload for people, pets, and gear in the vehicle.
I have a 2500 series Suburban, it's a different story from a 1500 series like an Escalade. I put 7 people inside, hitch up my 7,000 pound boat, load the back with gear and it doesn't even squat much.
Also, diesel engines have come a long way. Modern diesel trucks have more HP than semi trucks had in the 70s and 80s. They have about 50% the torque of modern semis. Since nobody builds a big diesel SUV people who want that kind of power just get trucks.
I can't understand why GM never put he Duramax in the Suburban. They offered their earlier 6.2L and 6.5L diesels in the Suburban and they were fairly popular. There are several companies that make Duramax powered Suburbans and you can find them for sale if you look around a little. If you want to tow with a big SUV I'd find a 2500 Sub. Get a diesel one if you really want some power. For my use, the 6.0 gas engine does just fine.