If you are into the ORV areas , there is one located just WEST of Redmond on the Sisters Highway... There are others listed in the Central Oregon Recreation map sold in Bi-Mart and at book stores locally....
The one outside Redmond is pretty basic, a bunch of dips to drive thru and a rock garden, not much of a challenge, it's big, but I think more aimed at Quads and Cycles.
I was there early in the summer while my wife attended a conference....So I had days to kill so I went there and drove around a bit but got pretty board with it...
There are lots of BLM land around, so keep your eyes open there.
Might try to hook up with others in that area, I didn't have much luck but I do have a post here somewhere prior to going over there....
I just returned from a trip thru to HINES and Burns and Burns Junction.....Lots of open land there as long as you close the cattle gates and observe the ranch rules if posted.
Good luck ! "BH"