The standard traverse route of the Stein Valley [Stein Valley Nlaka'pamux Heritage Park] starts at Lizzie Creek, just outside Pemberton. Approximately 91km of variably overgrown logging road, alpine trail, snow and rock, and finally well maintained trail, lead East from Pemberton to Lytton.
An early FKT: 35 hr, 45 min* - 2003.
* Travelled slightly less than the full traverse, as they hiked in the night before to Lizzie Cabin, which is about 3km and +1000' from the trailhead.
Dan Durston did the Traverse in 43:16, 8/13-15/2012. He reported as follows:
My wife dropped me off at the Lizzie Lake logging road Monday at 4:15pm and the climb up the overgrown road to the proper trailhead went quicker than planned, so I was at the trail head at 6:45pm.
My initial plan was to camp there and begin my FKT attempt in the morning. However, due to prior obligations I was very tight for time for this attempt so I decided I would start hiking that night instead of waiting to start in the morning. I knew this would significantly hurt my chances of a FKT, but completing this hike was more important to me than the FKT and I would still have a chance if I hiked through the night one of the nights. If I had waited until morning then there would have been a good chance I would have had to turn around as I needed to be on excellent pace to make my 3pm pickup (Aug 15). Even then, I would have been worried the whole time about making it out in time for pre-scheduled pick up.
So I hiked 6:45-10pm from Lizzie Lake to Caltha Lake, camped until 5:45am. With virtually no moon, it wasn't feasible to hike at night through the various cliff bands etc. The next day I hiked from Caltha Lake to Cottonwood Creek, which was a pretty big push with how overgrown a lot of the valley trail is (and extremely hot). Then I slept from 8:15pm to 5:45am and finished the hike yesterday at 2pm.
So my total attempt was 43.25 hours which included 26 hours of hiking and 17.25 hours of sleeping. The actual number of hours I spent hiking (26) was exactly the same as the previous attempt despite me hiking the extra 3km/1000' up to Lizzie Cabin as part of that time, the trail being considerably more overgrown in the old forest fire zones, and me being more spent to start with due to the 12km/+3000' hiked up to the trailhead (which was drivable in 2003).
So I did not meet my original goal of besting their FKT, but my time of 43.25 is a good reference for a true trailhead to trailhead time and one that could easily be improved upon with less time spent sleeping. I suspect the 26 hours that I was actually hiking would be very hard to beat with the present (ie. horrifically overgrown) conditions .