I have wondered about doing that too. My Northern Tier dataset, perhaps not current, contains 3380 waypoints, so any reduction to 1000 would have to throw out some that might be of interest to you.
5 rest areas
142 convenience stores
1988 route waypoints
More than half the route waypoints are superfluous with an auto-routing GPSR, present only to keep straight-line routes close to the roads. Those can go.
Watch for divided highways when setting up for auto-routing. Waypoints there serve both directions of travel. Many will need to be moved to the proper side of the highway to prevent the GPSR from generating bizarre routes.
An alternative is to write four overlapping sets of waypoints to a CD, along with one of the small programs to upload them. Carry a short USB cable and the CD into a computer store or the home of a local cyclist.
I have used G7ToWin, which runs well from a CD. Be sure to set all its options the way you want them and let it write its INI file before your burn the CD.