Hello,
I have to agree with the fellow locals. Two weeks before and two weeks after the rally are the best time to find a room but not in between. And as far as PD's go, you almost have to be 100 miles east of RC to avoid the "pay-by-day" privately run outfitters because of the proximity to the second largest "city" in SD.
Like Bark and chris said, call the BLM guys at Rosebud and Pine ridge for hunts. You may have to pay for a Indian guide, buts its usually a minimal fee for getting to a really nice town. I find that the reservations are some of the best places to hunt just because the people want you there, and are friendly; from my personal experience.
One thing you have to do if you plan on hunting a reservation is that you need to buy a varmint lisence for that particular reservation. One permit is not good for the whole state. And another thing is you have to ask for a daily permit if you're only planning on shooting for a day or two. They try to push the season permit obviously because it costs more. Buyer discretion I guess.
If you dont mind doing some serious leg-work and heading off in the direction of "where the heck am I at" you could get by for just gas money and hotel; but only if you plan on being here for a week or so.
South Dakota would love to see you here.
JA in SD
If you can think of anything I missed, just PM me.(Navarro, sorry about that PM you sent me, I just never thought to check my messages)