John Fedak just came off the Tahoe Rim Trail. He advised me:
… Hands down the best TRT leg is the 35 miles between Barker Pass to Echo Lake in the Desolation Wilderness over Dicks Pass. (With a side trip to summit Mt Tallac for its unparalleled Tahoe view)
To get to 50 miles you’d want to extend that to either Tahoe City or Big Meadow (North and South respectivly) Tahoe City is logistically better (The trail goes right into town) but the latter is probably a bit more scenic. …
I’ve decided to hike the section marked in red:
Starting Echo Lake and hiking up to Tahoe City. I’ll begin Monday, September 22nd. (I’ve got an Adventure Race on the 26th in Tahoe.)
John posts a hiking site rich with annotated hiking photos. Check his most recent trip: Tahoe Rim Trail: Echo Lake to Big Meadow
One of his pics from that trip:
Stairsteps in a manmade section of the trail.
Leave a comment if you have any more advice. This is my first hike on the TRT.
besthike.com 
Looks to be a great hike and the option of a summit along the way!
Then ready to go with that adventure race.
DSD
A cab ride from Tahoe City to Echo Summit is going to run you about $150 bucks. (I think that translates into about $20 Canadian these days)
You’ll need to stop in town and pick up an overnight permit prior to your start (they’re going to try to talk you into a bear can) The backpacker lot is above the main Echo Lake parking lot. The trailhead is down near the outlet to the lake.