As some have stated the walk in is first come first served. I wouldnt worry to much about it. There are thousands upon thousands of acres of public ground. And depending on the area you could probably get on some private ground if you tried. And all you need is your license and tags, and they are good the entire season. And I am fairly certain they are over the counter. I dont know about the area though but I would guess there are still pure bred Rios up there.