This right here! Experience…
This right here! Experience with several low mileage gm trucks of this era, including an '08 with 50k.miles, has shown me 1st hand that frame rot is a horrendous issue on these trucks in Northern states. The "fully boxed" frame beneath the cab is really just a sheet metal tube welded up of MANY pieces. There are laps everywhere to invite salty water to creep in by capillary action. There are also holes all over the place for fixture pins. These allow the water and dirt to enter the tube where it rots from the inside. Much like looking for termites in a house, you want to take an icepick and probe the frame . Often it will go right thru. I've seen trucks that look like show cars on the body with 12-16" long sections of perforation in the frame.
I wouldn't hesitate at a 200k mile chevy from TX but ANY '08 from the snowbelt states is highly suspect.