Check the route on bycycle.org I couldn't make a link work for some reason. Starting: longitude=-122.675657, latitude=45.550722
Ending: longitude=-122.693939, latitude=45.260389
The toughest part is getting through Milwaukie and riding on/around McLoughlin or 173rd. It'll be a long ride for your co-pilot, but there are quite a few parks along the way.