I have to agree about cancelling you reservations. You have locked in half your trip. Reservations are not all that hard to come by, except maybe some coastal campgrounds or busy cities.
At some point, you will be talking to some locals (hopefully) and decide to attend some 3 day event or whatever, throwing off all of your reservations. Cancel them now and be free...
Instead, I would suggest just having a general plan, and setting a goal to reach California in around 40 days, Vancouver in another 30, that sort of thing.