I will most likely be hunting it or fossil this year. On forest circus website, they have a map of all ohv roads that might answer your question though.
There is 63 sq miles of travel management area in heppner and fossil units combined. You should be able to look it up on the odfw website int in the access map section. Or give heppner odfw a call. They have maps. 541-676-5230 Hepper field office