Haven't driven the new colorado/canyon but I can't imagine it would be comfortable at 6'9. Although I don't see how the Ram is either, I'm 6'4 and have smashed the button on the top of my hat against the roof of my 17 Ram 2500 on big bumps (btw, ripping hat buttons off with pliers is the best 30 second you can spend). Must be my driving position.
I vote keep the big rig and get a beater. I love keeping my megacab in the shop until the weekend, it's like a reward for me to park my other DD truck and drive the new one, with or without the camper.