I once hired a guy to do a block wall for me. Was doing concrete and block work with a half ton chevy. Noticed I worked on stuff. Asked about putting more spring on the back. I pointed out that more spring won't do any good as he still has a half ton axle, a half ton frame, half ton brakes. I happen to have a 3/4 ton truck and pointed out how much beefier the parts are to handle the weight. It would be cheaper to get a different truck.
As for ride quality, my '77 F250 camper special (you get a rear sway bar with the camper package) actually rides pretty good. Not as good as the really new stuff out there, but for the vintage it isn't bad. I know trucks 20+ years newer that don't ride as good. But the real new stuff rides very good.
There is a middle ground that might work for you. Nissan XD, more than a half ton, less then a three quarter ton. Has all the HD frame, brakes, axles, etc., but is designed for a daily driver unloaded as well. Hellwig has the shop truck setup with a camper.