Some spots in Nebraska are all I know about along US 83.
Directly on US 83 in the Nebraska Sandhills is Valentine National Wildlife Refuge. Some NWRs have campgrounds--dunno if this one does. Southwest of the town of Valentine, the Merritt Reservoir is home to a State Recreation Area and a NF campground or two within the Samuel McKelvie Nat Forest. A little south of Valentine NWR is the town of Thedford, where US 83 crosses NE-2, the "Sandhills Scenic Journey" highway. Around 10 mi southeast of Thedford is the Nebraska NF campground at Bessey, on the west side of Halsey. Nice facility and I've spent 3 nights there. Only problem with anything along NE-2 is the coal trains which run 24/7. The access road to the CG off of NE-2 crosses the tracks, so the train horns blow all night long.
Cool trip! US 83 is the 4th longest highway in the US. It won't take you to the end of the world, but you can dang sure see it from US 83!
Foy