I think I would skip the kayaks altogether.
Bikes I would bring for sure, it is handy to have when exploring a campground, and to burn off some energy after a long drive.
I dry camped near "Wall Drgus" in Wall SD. It is a interesting place, but more hype than anything else. A day trip to the badlands south of town might be worthwhile for the views. That is what I did.
I also went to DeSmit SD to visit the house on the Prairie made famous by Laura Ingalls Wilder. They have a 3 place campground on the property, and I spent the night. Electric only. I did not take the time to see her homestead north of town though. I did spend a hour or so looking at the new John Deer Tractors outside a farm equipment dealership though. . .
As for going south to Moab - I might recommend that. Arches NP, and the area around there is interesting. You probably will not get back to the area for a really long time. Probably would park in town, and spend 2-3 days driving around sightseeing. Then take highway 128 back towards the interstate. You can head east to get back home via Denver. There should be some great places to camp in the woods along the way in Colorado.
Have fun camping!
Fred.
