I'm not aware of any maps available in a format for loading on a GPS, though you may try a site like EveryTrail or Motion Based (Garmin Connect) to see if there are any public GPS tracks available there.
If you happen to find tracklog, or map data I'd like to know about it for the Ontario Trails Project, which is a map of Ontario Trails that works rather nicely on an Oregon.
Thanks for the info!
I'll give you a heads up if i find anything!