It's doable, but keep a close eye on the weather report - if a big storm is coming be sure to take cover somewhere.

As ploeg mentioned, the short days are an issue. It could be very cold in the morning which makes packing up difficult. It may be very cold in the afternoon as well, so you'll want to be in your tent early. That doesn't give you a whole lot of hours to pedal.

Chances are you'll have lovely fall days for the actual cycling part of your days. We loved cycling through the USA in the fall - it's beautiful! It's not so hot so you're not drenched in sweat and you've got the lovely fall colors... It's really a delightful time to ride. Just be prepared for the cold snap that you're sure to encounter.