Well, as luck would have it that is exactly what we tow with, down to the year. We have the complete tow package. However, we don't tow an Airstream (maybe someday). The trailer we tow is I believe 3500 pounds with full propane tanks but no batteries or hitch. I figure once we are loaded up we are easily at 4500 lbs and more if we are carrying any fresh water.
I checked the payload for four adults and loaded up I think we are maybe a 100 lbs under max payload.
Also, we just pulled the trailer over two 8% grade mountain passes (8% up and down), max elevation 5000 ft, with the Suburban.
It made it up OK, not great. We dropped to 35 mpg a couple of times and the rpms were up to 5000 a few times. The good news is that the temperature gauge did not budge. We got better at managing the gears on the second pass, but still dropped to 35 a couple of times.
Here's the real difficulty. Even with trailer brakes, I don't think our brakes are up to the job. We started pulling over every time we dropped 1000 feet to let the brakes cool. Both Suburban and trailer brakes were extremely hot a couple of times (before we started stopping every thousand vertical feet). I was afraid we would warp the rotors, but we didn't. I used the currently recommended pulse (snub?) method of braking. I'm looking at the blister I got on the end of my finger from touching the rotor.
We were careful because we have had the Suburban brakes fade on us coming down other mountain passes, even without a trailer.
I think it was on this site that I read that you can upgrade your brakes and rotors. If you go with the 1500
you should do that. I assume 2500 has better brakes, but I don't know that for sure. I'm thinking about upgrading our brakes, but I don't want to do a lot of work on a vehicle that we might not have much longer. It's got a fair amount of miles.
Anyway, just my 2 cents. In general, I love the Suburban. It's a workhorse and very reliable. Hope it helps.