Sounds just like a few of the rural roads around Vancouver, Wa.! Between Battleground, Hockinson, and the freeways there are a few leftover farm roads which serve as high speed arterials.
I used to live out there. I moved.
Do you have some place to bail out? These roads out here don't, I'd end up going headfirst into deep mud at the bottom of a potentially canyonesque ditch! In that case, I'd go many miles out of the way for a detour. Some heavy duty illumination turned on at all times, day or night, would help. But people get crazy and make a run for it anyway, so be ready to bail out! Is there room on those roads for a truck to pass you while another truck is passing in the oncoming lane? If not, you'll have to bail out for overtaking traffic sooner or later as well.

My favorite detours around these kind of roads involve somewhat narrower roads, with bumpy pavement, they're twisty, a bit hilly, they've got a few stop signs and I have to make a couple of doglegs to put my route together. Which means no one drives there unless they absolutely have to! They're driving half an hour at least just to get anywhere, so they take the fastest roads to get it over with. This turns a ten mile drive to my parent's house into a fifteen or sixteen mile ride, but it's just me and a few residents on those roads.