I'm super late to this thread, but I'll throw in my opinion on a Colorado ZR2 Duramax. I realize this is over your budget, but keep in mind that a lot of "overlanders" buy a stock vehicle and then proceed to add thou$ands in modifications to bring it up to the capabilities and comfort they are looking for. My approach was to go purely stock and minimalist. My 2018 ZR2 has exactly 3 modifications: A power outlet in the bed for a fridge ($20), an undercover bed cover ($1,100), and Fab589 Shock skids ($99). This is one of the few choices in a new vehicle where you don't have to immediately upgrade tires.
This thing works great and I can hang with my friends off-road without issue. I'm no longer the weak link and the stress level is low. We do mostly desert and dry mountain trails, but it gets regular use in the snow in the winter on roads and the stock A/T tires work great on snow and ice.
No, you won't be sleeping in the bed in the shortbed version unless you get a cap and one of those tent extensions that extend over the tailgate. My cheap/light solution is a swag, but there are tons of other better options if you want to spend more $$. Maybe later when I have more time to camp and travel.
One thing that isn't well known is that it has a larger than 21 gallon fuel tank. At about 23 mph average, I always get at least 500 miles between fillups. The trick is to slow fill the last 2-2.5 gallons because Chevy intentionally did something to make the pump shutoff early. I have put in as much as 23 gallons after the reserve comes on. I've gone as far as 550 on a single tank, which would be almost 24 mpg for 23 gallons. My off-road average is between 15-18 depending on the amount of low speed crawling.