I did the trail about 15 years ago in a '64 Series II, then again in a Discovery maybe 10 years ago? The second time we spent an extra few days and camped out by a small lake. It was worth taking the extra time, just watch out for bears! I had a few close encounters. Trying to scare one away from camp, I saw ~25mph in the Disco, and the damn thing was still out running me!
When are you thinking on going? Probably can't make it this summer, but I'd really like to make the trip in the D90.