Drive/Tow/Hunt in a 2011 Duramax crew cab, long bed. Mirror what most everyone has said. Letting air out of the tires makes a real difference on the washboards and dirt roads in general, but rough pot holed roads are still brutal. I've been amazed at how well it's taken care of me when in 4WD low when on some gnarly steep/bumpy hills, along with mild snow (4-8") on Wyoming hunting roads.
Since it's a big decision, I think I figured how to upload a video of my duramax on a steep, dry, uneven road. Can't see in vid how steep it is as the phone is pointed a little down in the holder, but to me as a relative rookie, it was pretty pucker filled ride with my hood aiming at the sky unable to see the road. Got stuck for a sec right before the top on the steepest part, but luckily with a stronger throttle push made it over the top.
Rookie mistake though as I didn't air down tires before entering that area, as I didn't know how steep it was going to be. 70-front / 80 rear is FAR from ideal for traction. Barely made it but did:
I run the K02's in the tallest size that'll fit under stock suspension. Towing the mobile office/base camp (25' bumper pull, c. 9k lbs) is great!
If you have the backup of the sxs/atv for most times and the 3/4 ton for towing and general getting around, sounds like a darn good combo.
On the duramax forum they mention "sulastic shackles" for the back to improve the rough ride, but I know nothing about them or if they're any good.
Cheers
S