Four-lane highway, narrow shoulders in parts, no shoulders in some sections, speed limit of 65 mph dropping to 60 mph
And they are usually running about 70 mph. Humm, how heavy is traffic? Would you feel comfortable walking on the side of the road with no shoulders?
For me the risks would be too high, I'ld take the longer route and carry a cell phone for help or cab if need arises. I have one 1 mile stretch of traffic at 45 and me at 15 and that is the most I will tolerate in speed differences.