Don't want to derail your thread but I didn't even know there were walleye in Oregon. If you get a chance, PM me or email about where they have them here. Cool fish! Thanks and best of luck on your trip.
Introduced species that survive usually do very well, there aren't any natural predators in the system. Carp are an example. When fish like walleye do good, everyone is happy. You can't eat carp, so people generally dislike them. Well except for the Russian and Asian dudes that somehow eat em.
That's why we have larger bass, carp, walleye, perch and bluegill than other systems well known for them.
As for a guide, try steve the walleye guy on ifish. I hear he's real good