It's pretty difficult to get ahold of the guys, but check out Black Hills 4-Wheelers. They do runs every now and again, great group of guys. You can also try Black Hills Jeeps. They also do runs through the hills. I would be happy to meet up with you for a run and stuff but I leave a few days prior to your arrival for a few months. Hopefully someone will get in touch with you to set something up, but you're not likely to find that person on here.
Worst case scenario you can check out Camp 5 for some good wheeling, and if you get there early, you may meet someone at the trail head.
[SIZE="3"][B]Check the air tires, thats where the power is generated.[/B][/SIZE]