SUGV1,
It is all about fun and there are no rules. They are considered varmints. I have shot the youngsters with 22 rifles and pistols,
all the way up to a 30-06 with 110 HP.
Now I mostly use a .223 with light bullets, but I still bring out my .220 Swift for "special effects".
Bring good ear protection!
There are sharp rocks, and cactus out there, so bring a scrap of carpeting to lay on 6'x6' is about right.
Otherwise you can rig up a small portable bench of some kind.
Some guys shoot right off the hood of their vehicle.
I bring a tent and sleep right in the dogtown, so I am out there as soon as the sun comes up and shooting before breakfast.
Google search for hunting info in each state you are thinking about.
Here is a picture of my youngest son shooting off a homemade shooting bench, very portable. He uses a bipod but I prefer a sandbag. Get comfy and bring sunblock. There are no shade trees in South Dakota,
whelennut