I think it's wonderful that you are considering becoming an historic "district" under the National Register of Historic Places designation. A few point to keep in mind: Not all the cabins in the tract or vicinity need to be included. Some may opt out, and that is fine. There is always strength in numbers when dealing with the Forest Service or government agencies, such as the county. And yes such a designation would inhibit the FS from removing or reducing structures. I strongly urge you to contact your State Historical Preservation Office (SHPO) for advice on how to proceed and ask them to recommend a consultant with experience in Historic districts for you to work with..