I posted a video of the activation and hike.

There are a couple different routes to the top. The hard way starts at the Siouxon Creek Trailhead, involves a lot of climbing, and is quite far. The easier route starts at the end of forest road NF-6403 and climbs 2.75 miles to the exposed summit of Siouxon Peak. NF-6403 includes about 8 miles of single lane gravel road. I recommend a high clearance vehicle - and carry an axe/machete to deal with downed branches. Most were cleared on the drive up. The trail has spectacular views of Mts St. Helens, Adams, Rainier, and Hood (if clear). It's a decent climb at 4000+ feet. There was one spot about .5 mile in where a recent landslide occurred, it's passable, but heart-racing.

Directions:

From Portland take I-84 E to Cascade Locks Exit 44.

Cross Bridge of the Gods to WA, and turn right onto WA-14 E.

Turn Left at Wind River Road towards Carson. (there's a good gas station on this road if you need last minute beverages or snacks.

Turn Right onto Meadow Creek Rd / NF-30

Slight Left onto Dry Creek Rd. which turns into NF-64. 

Turn right onto NF-6403 until the road ends. The trail begins at the end of the road. Ample parking at trailhead.

Once in the forest the roads are NOT marked, but Google Maps or GPS does a pretty good job getting you there. The trail is pretty obvious - just keep going up, close to the top the trail will veer to the right or left, go left for Siouxon Peak, or continue right and you can hit Huffman Peak. I'll save that activation for an overnighter.

Activation:

Thanks to the chasers and locals that made contacts, that was thrilling given a suspect antenna hang, and a faulty radio. Got a 40 mile simplex call back into Portland on 2m/5 watts (HT) which was exciting. Worked 20/40 but didn't make any contacts on 40m. The summit is exposed, but about 10 feet down from the summit is a flat ledge where the fire lookout used to be, and there are trees you can use to hang your antenna. I'm still rolling the G5RV junior - and couldn't get a good hang. Fortunately I brought a 16' painters pole, so used that to get a little height. Not ideal, but it worked.

This summit has fantastic views, and I spent a very enjoyable afternoon up there. Stopped in Cascade Locks on the way home for much needed soft serve.