Peak 3700 is a bit of an adventure, but certainly do-able summit near Detroit, Oregon. You'll follow a long-abandoned logging road and head cross-country for the final ascent into the Activation Zone. There are no views and the final ascent is very rough, but you get to enjoy the quiet of a second-growth forest.
Here's an out of the way summit south of Prineville, Oregon with nice views and plenty of quiet. The drive towards the summit on Highway 27 is along the Wild and Scenic Crooked River and is lovely in itself with nice camping opportunities.
The access road for Horse Mountain, about 12 miles SW of Service Creek, Oregon along Highway 207 is posted "No Trespassing."
Rancheria Rock is south of Fossil, Oregon about 9 miles. Rancheria Lookout Road heading up towards the summit is gated and locked and posted "No Trespassing." The summit appears to be a fomer lookout and likely has some RF comm sites.
Peak 3930, about two miles north of Fossil, Oregon appears to be on private property behind a gate.
Zero Butte is just west of Condon, Oregon and is an easy drive-up summit. Take Highway 206 4.5 miles west from Condon and turn (left) west onto Richmond Road. Continue 1.5 miles to an unmarked dirt road heading off to the left. This is about where the unexpected subdivision ends and where what looks like a former military installation begins. The dirt road was easily passible in a passenger car for the 0.9 miles to a fence and a gate where the high point is located.
Grizzly Mountain is an easy drive-up summit about 9 miles west of Prineville. The views are great and the road passable in a passenger vehicle - perhaps slowly in the rocky places.
There is a sign posted at a gate that reads "No Trespassing - Private Recreation Lease." Access to the gate is along mostly graded gravel roads. I didn't pass the gate to hike to the summit for obvious reasons.
This was a joint SOTA expedition with me, Bill WA7NCL, and Rich AC7MA. See photos here:
https://photos.app.goo.gl/JWPaWiE5l7v0Vmwm2
Goat Mountain: (1.1 miles, 1,100 ft)
A GPS (with land ownership) is recommended – to help stay on the unmarked public land.