Wickiup Mountain is a summit on the edge of Astoria's Bear Creek Watershed, from which they draw their water, as well as an active radio site. As such, access from the south is gated, and road access from the north stops just shy of the summit. What followed is one of the thickest, roughest bushwhacks, mile for mile, of my SOTA career, but it was nice to tick this one off the list. If you route find a little better than I do, you might have a better time, and if you hit it earlier in the year, the die-back of the brush might benefit you.
Start from US30; head south on a gravel road at 46.14571, -123.58297 which stays in pretty good repair as it ascends on private lands open to recreational access when fire danger is low. Turn hard right to go west at 46.1243, -123.5676, and then left to ascend the ridge, and then left again after half a mile to take the road to the summit. The track is available on peakbagger as well; the track can be downloaded at https://www.peakbagger.com/climber/GPXFile.aspx?aid=407541&sep=1. CalTopo, my map of choice, do not show the roads accurately past the first two turns, but this track follows them exactly. You will come to a turnout with a large space for parking at 46.10705, -123.58151; this is where I parked my Fit and headed up.
I don't have a good recommendation for you on this ridge, other than don't go west much; there is an old road somewhere in there that might provide better access if you can find where it comes out, but I only saw it on the way down. Stick to the ridgeline, as there are plenty of opportunities to end up off of it, and try to find bits of more mature forest to push through; anywhere that looks like a clearing full of brush will be worse to push through than the baby trees are, and the whole mess is a slog of downed trees, downed branches, and easily-found holes in between them. On the other hand, it's about a quarter mile of this, only, from the car to the summit, where you'll find a radio tower and accompanying buildings, and plenty of space to tuck off on the side.
When I approached from the south, from which side the road ascends to the summit, I found a hand-welded sign saying this is a closed watershed owned by the city of Astoria; all access is restricted, to all lands draining into the Bear Creek watershed to the southwest of the peak all the way around to Astoria, essentially, so do stay sort of on the north side of the peak, and you should be more than fine.