Bad hopping when backing up, is it me or a problem with the truck?

I assume your using low reverse if not give it a try .. I pulled 100 k with that setup in the past and it was smooth in low reverse ps you have 3 reverse gear

 

It could very well be that you're not used to it, and any air ride will get hopping easier in reverse than forward, but there could be something wrong amplifying the problem.

Those Pete clutch linkages can get tight, I've never been a fan of that design, but they're still using it. You have 6 places that can tighten up, 4 rod ends and 2 cross shafts. The cross shafts have grease fittings and if you do not have the remote lube, you'll never find them if you didn't know they were there. They are usually fine with the some grease. But the rod ends often tighten up and make the clutch release a little jerky. With the engine off, just push the clutch all the way down and back up really slowly. If it's not smooth, something is tightening up. The shaft right off the trans is fairly easy to get to to check the end links, the other one is not so easy to see, but that is the one that tightens up first.

Also check the drive shocks, engine and cab mounts, all of those can amplify a clutch release problem. Cab and engine mounts would need to be pretty bad and probably make a clunking noise at that point, but it doesn't hurt to look at them.

 

Some auto shifts have the “hill assist” switch turn that off when backing, it’ll only stay off for about5 minutes or ontil you get to like 20 mph forward