Summary - Peak 4020 and Aurora Mountain, southwest of Mount Saint Helens (near Ape Cave), are easily accessible by 2WD. I did them as a seven mile RT traverse hike (two thousand feet of up) with a couple of short cross country sections. The summits are forested but the views of Goat Mountain and Mount Saint Helens along the way are terrific. From Portland, plan on spending roughly four hours round trip driving on good roads, have a backup plan if two meter contacts are sparse, and bring bug juice for Aurora. This is a fine hike and two peak activation.
Long Version - While you can drive to the summit of 4020 and hike Aurora from Red Rock Pass, looking at the map I decided there might be a good traverse hike along Cinnamon Trail. The google lady will give you satisfactory directions; from Portland the drive took a little less than two hours to the access point (46.8.0096, -122.15.0902) on FR8303. The road is paved or well-graded gravel the entire way and there are places to pull off the road near the access point.
Once parked, look for an easy-to-access spot on the north side of the road. You'll cross Cinnamon trail within a hundred yards or so. Turn east and follow the trail for roughly a mile to Aurora Mountain. You'll climb about six hundred feet, leaving the trail to hike up the final ridge. If you probe a bit, you'll discover what seems to be an old road that spirals up around the south to the summit, which is tree-covered and without views.
I had on-and-off ATT digital service here and I didn't turn on APRS. I didn't make any two meter contacts but I didn't try that hard, so you may have more luck than me. Getting a mast and EFRW up was easy. The mosquitoes were thick and hungry, bring your bug spray. When you are finished, pack up and head back the way you came. Be careful it is easy to get turned around and miss the path, especially if you try to follow one of the "shelfs" back down.
The hike to 4020 from the summit of Aurora is about 3.5 miles and climbs about 1000 feet. With the ups and downs on this part of the hike, plan on 1400 feet total up. The trail is easy to follow, mostly through the forest, has a few steep sections, and offers excellent views of Goat Mountain and Mount Saint Helens. The trail crosses the road to 4020 several times and goes all the way to the summit. I didn't see any boot prints but did come across deer and, maybe, bear track.
At the top, I tagged the summit (about seven feet higher than the trail) then wandered about fifty yards to a very large old stump ready to hold a mast. Two meters was quiet, so all of my contacts were CW on HF. Lots of relatively local forty meter action. ATT service was mostly out, so I spotted using an inreach and SOTAMat. Not sure why, but I didn't turn on APRS. And... no mosquitoes either! My longest contact of the day was SM2SUM from Sweden, on twenty meters.
I highly recommend this traverse: two summits, seven miles, thousand feet, easy access, and nice views along the way, what more could you ask for?