You're right about the terrain. Most of that area is quite flat. The link below is to a Wikimapia map centered on the BTG VOR (zoom in and you can see the VOR calibration/test antennas around the building). Ariel, WA is due North. Victor 23 runs into BTG from 329 degrees North, which is ~parallel to I-5 between La Center and the I-205 junction. Click "view" at upper left to change view to terrain/satellite, etc.
Second link is to photos of the Fargher Lake area, which is just right of center at the top of the Wikimapia map. The terrain at Fargher Lake is very typical for that area.