I have a '11 Silverado 2500 HD with the Duramax/Allison sitting on a 4" Cognito lift and 35x12-18"s. It was my daily driver until just last year, and it's always been my tow-rig. I still have a 5th wheel Toy Hauler I pull with it, along with a few other trailers. That said, it's done a lot of what most would call "Overlanding" for years. I've often gone 3-4 hours out dirt roads with it to camp, but I guess I never saw it as "Overlanding" because the roads themselves weren't particularly difficult roads, and sometimes I was going to my family cabin (to be clear, it's an old-school real cabin, you don't even sleep inside, but it's still "cheating" I guess). The truck is extremely capable, comfortable, and the space for "stuff" is great. I've also recovered many, many rigs with it from soft sand and dirt.
Now, that said, I still didn't pick it as my dedicated Overlander. That decision was mostly based on size and IFS. I've never had any problems with my IFS, but it's not my first choice for wheeling, and I want to Overland the "tougher" trails (partly because I enjoy the challenge, and partly because it gives you access to even more remote and desolate locations). As for size, the thing is just Yuge and heavy at about 8500lbs without me or gear in it if I have the aux fuel tank full (I have a 60 gallon stock-replacement fuel tank under the truck for diesel, but I also have a 65 gallon fuel tank/toolbox combo in the bed I use for gasoline for my "toys" on non-Overland type trips). Finally, I like this truck to stay looking good, so yeah I don't want to trail stripe it up. Sure, I'm that guy (with my truck, not my WJ).
That said, there's definitely a part of me that wants to SAS this truck and make an Overlander out of it. Again, the space is awesome. I like the idea of a truck for an Overlander so you can run a bed-rack that's not super-tall and have the top of your RTT even with the top of the cab of the truck when stowed. I already have a ton of fuel on the truck as I mentioned, I could never see needing more than the 60 gallons of diesel for me, which would mean I could have 65 gallons of gasoline onboard for all the other rigs in my group and we could really extend our trips. I also would have tons of room to add a decent amount of water storage, and room for storage for "dirty" things you don't want inside (say firewood when we're going to more barren areas, fire-pit to have fires more easily/safely, spare parts, garbage for the whole group, etc.) and a giant cooler. The cab of my truck is also super-comfortable for long-trips and would provide plenty of space for the "clean" stuff (clothes, food, etc.).
Anyway, I guess my point is that I think it WOULD make a great Overlander, especially if you're content with IFS and slightly milder trails. For me, I wanted something smaller/lighter and solid axle front (and rear).
Doing some Overlanding out of my Silverado about ~3hrs out dirt roads from the nearest electricity, phone signal, etc:
Yeah with a full size rig, I'd think you'd want to pick and choose your trails wisely. I know I would. I'm also not a fan of trail striping, but once you're committed there is no turning back lol. 60 gallon, holy smokes!
I had a 2005 suburban z71. I loved the size of the rig. By the time I had it, it had many issues from sitting in the driveway for years and not being moved. I spent thousands fixing it up to the point where it was good and reliable, but the rusties started taking over. My wife and I are looking at starting a new tour business for Central Newfoundland. I am thinking the suburban would be the ideal rig. I need comfortable room for me, her and 4 passengers. The burban fits the bill. Plus I can outfit it with some off road goodies to get our clients to more places. Even with the 3rd row seat in place, there's still plenty of room for gear etc. I was looking at the commander too, but they are not quite large enough. I think the suburban would be the correct vehicle for our business.