Give us a link to a Google Map of the route!
When I ride my bike across the country, I do thousands of miles on state or national highways with 2-3 foot shoulders and 55-65mph speed limits. Generally, they aren't particularly dangerous, despite what people who have no idea what they're talking about might say. It's certainly possible that your particular route is a bad one, due to traffic volume/type, road condition, visibility, driveways/intersections, etc., but it's impossible to say without at least seeing a virtual version of it.
If you're like me, you'll find your own equilibrium. Start off on the longer, "safer" route, and then as you become acclimated, you might say "fuck it, this safe route is way too long", and gravitate more towards the direct route. And then if that one seems to scary, you might switch back, or find another option.