With Ft. Huachuca close by, I know of a number of retired military in that area and some who camp. I've camped before over by Patagonia RV Park which is about an hour away from Tombstone since there are, I believe, about four wineries in the neighborhood and, they have an annual fall festival there.

I suspect you will find all the time you need in Tombstone to be one or two days. I would recommend staying in Benson (shopping and easy access to I-10 to take the 45 minute drive to Tucson for more choices) or Bisbee (we love Bisbee and it has the Queen Mine RV Park) and visit Tombstone for a day trip. The SKP park in Benson is nice if you are an Escapee and there are other choices. We have also stayed at the Passport America park in Naco, Turquoise Valley, but it might be a bit too far from Tombstone for you. The general area has a lot to see.