Alaska Off Road: Who has been there, done that?

Several friends and I are planning a trip to Alaska, July or August '03. We are experienced off road riders, "A" enduro.
I have been unable to find out if there is significant off road riding in Alaska, or mainly just gravel or paved roads. Colorado mountains have a wealth of trails over passes and in the mountains that are excellent riding. Are there similar trails in Alaska? We are trying to decide on large Dual Sport bikes with high speed capability such as BMW 1150 or 650; KLR 650, or KTM LC4 or LC8. Another option we are considering is trailering KTM RFSs that we all currently own for off road riding.
The Alcan highway is essentially paved and we are wondering if a pure off road bike will be a waste up there if there are limited dirt trails? Is August too late?

Thanks Tony, I have not seen that site.
Also try:
http://www.advrider.com/forums/

Thanks for the advise. I have found a good used KLR 650, probably a good choice for the trip.