Lived in Hermiston just north of the Heppner unit for several years. LOTS of hunters, but there are some road closures. I used to ride my mountain bike as far as I could and would start to see elk and deer about 2 miles in. Lots of road hunters slaying every spike and forked horn buck in the woods. It can get pretty crazy. There are areas to get away from hunters, look at your map for areas without roads or road closures.
Good luck,
Rich