I'd read about this river falls in a post online a while ago. Here is an updated version: https://southwestwashingtonpaddletrips. ... orth-fork/
I've spent some time up there and I've driven on the logging roads up above. At one point my phone's GPS indicated I was above the headwaters of the Palix and got out to scramble down and see how close I could get. Answer: not very close. It's incredibly steep, wildly brushy terrain.
This is a forum for trip reports that pre-date the Portland Hikers forum, trail photos from pre-digital era, or any other discussions that focus on trail history.
It's been a number of years on this one, but it looks like coming in from that ridge on the east is the best bet.