Indian Spring Butte is very near Strawberry Mountain (W7O/NE-018) and it is possible to summit both in a single day. It is 0.8 miles one way and 600 feet of gain. There is no defined trail, but the access is straightforward because of minimal undergrowth under the tree canopy and it is an easy ridgeline to follow.
2023 Update:
See latest update from Guy N7UN about DNR altering some roads in this area!
http://www.pnwsota.org/blog/n7un/2023-october-22/new-access-information-mt-mitchell
2021 Trip Report:
I activated Monte Carlo in May 2021 and wanted to provide updated information about the summit.
It appeared to me that access to Grayback Mountain was possible to summit from the South staying off of Yakima Nation Lands. I also found a trail map with access and photos of the summit from 2019 here: http://www.willhiteweb.com/washington_fire_lookouts/grayback_mountain_lookout/map_300.htm
Hauk Butte is a 9.5-mile RT hike with ~2000 ft gain located Northeast of Dog Mountain and Augspurger Mountain north of the Columbia River. Reaching the summit is possible entirely on logging roads, which go right up to the exact SOTA summit. At the summit, you are surrounded by trees on each side of the road as the summit has not yet been logged. This came in handy when I activated during 20-30 mph winds: the trees made a good wind break.
Shingle Mountain summit is a 5-mile out and back hike located Northeast of Dog Mountain and Augspurger Mountain north of the Columbia River accessed from a national forest road just before reaching the Moss Creek Campground. I marked both “Easy Trail” and “Treacherous Trial” above because like many SOTA summits, you get both on this one.
K7EEX trip report for Wolfe Point (http://www.pnwsota.org/blog/k7eex/2018-january-13/wolf-point-oregon) mentioned a possible south trail. This report confirms a south access to Wolfe Point.
If coming from Cedar Butte activation, turn off of the road at: N45.57747° W123.63990°. Park at N45.57731° W123.61891° the trail looks like a small drainage (see pic). It is not maintained and hard to follow in places but you can get to the top from this south access.
Underwood Mountain is a 2 pt summit Northwest of Underwood, WA across the river Northwest from Hood River Oregon. The start point is about 4.5 miles off of highway 14. It is an easy 3 mile hike to the summit with 1400 ft elevation gain on forest roads closed to motor vehicles. There is a short 250 foot doable bushwack to the summit. It would be a very feasible mountain bike activation.
This summit is attained in a 4.5 mile, 3500 ft elevation gain hike with well maintained trial for the first half and reasonable trail with loose rock the rest of the way to the top. The trail head is easy to find once you know what you are looking for. There are a few key GPS waypoints that ease your way tremendously. I would not have been able to make this activation without tips from KC7DM, so a huge thank you to him.
This summit is a progressively more difficult climb as you ascend. The activation is challenging but rewarding. The route I took starts with an easy well trafficked trail, but the second part of the ascent has no trail and involves navigating through the Angell Basin which consists of areas of large granite boulders.