Camping/hiking/fishing trips in remote areas, I would find an area to target. Then look at the arcgis PFBC Trout Streams map. since remote and unknown - I would start with class A streams.
Once you find streams in your target area, start googling hiking trails there. alltrails is a paid site, but without paying one could find hiking trail names to google specific trails. You are looking for hiking trail that intersects a stream (class A).
Some trails are long, you don't need to hike it all.
Some trails have "campsites" - your google search will let ya know. Depending on what public land you are on, you could camp anywhere (there are regulations to check, like cannot camp within X feet of a stream.) state forest land would be my suggestion.
Then, parking. Trail maps help with this. There is enough parking but some do not permit overnight parking, so do some research. Again, trail information should discuss parking - especially if is a longer trail where overnights are more common.
I would suggest not to go bush whacking - find trails to the stream.
Another consideration. The trout map is good. However, in my experience some of the mountain streams are shorter than the map indicates; up near the source it might be barely a trickle. So, avoid access to the stream near its source.
Have fun!
Hammersly (since mentioned) has a decent old growth forest which is worth checking...no streams in the old growth area though.
Lastly, Trout Streams map has state gamelands, state forests, and state parks - showing public land