The Lewis and Clark Route - How many days?

[KWelland]

I hope to ride the entire Adventure Cycling Lewis and Clark route during the summer of '05 solo and self-supported. I have one other long distance tour under my belt - the Trans Am route 10 years ago, and have completed multiple 1-2 week tours.  I rode the Trans Am in 55 days. I am wondering what a realistic number of days would be for a fairly strong, though not terribly fast, rider might be? I will be riding an old hardtail mt. bike.  I am a teacher and have mid-June til mid-August to complete the ride. Thanks.
Kathleen