Yeah man. I feel the exact same way.
I have the same issue with my 2015 2500 Silverado WT. So much so that I've replaced the cushion, talked with dealership, and even contacted custom seat manufacturers. I'd say the best remedy is contacting a company called Sheel Mann. They make amazingly comfortable seats and their sales team is extremely helpful.
And for the record, everyone in this thread saying comfort is relative, or that is depends on your size, that's BS. These seats are pretty uncomfortable for anyone compared to competitors seats. And for someone with a bad back, they're a nightmare. I'm 28 years old and in very good competitive shape. I'm 6'2" and 190lbs.
The biggest issue is that the ergonomics are terribly designed. Your knees should never be above your hips while sitting. And this seat leaves your knees a good half foot above your hips for a guy my height.
My hamstrings hurt after half an hour driving in the OEM seats.
But the Sheel Mann seats with the customer made seat bracket changed the game for me.
Not cheap though! It was the most economical solution for me, but still ran me 2k.
Good luck!