I personally never had a problem with any of 52 N (and I ran it A LOT), maybe they're just not paying attention? It can be a nasty little stretch of road but so can a lot of roads. And yeah, the 40s CAN be, um..."interesting", for sure.
The Blue Highways are more fun and offer better scenic adventures while offering LESS traffic.
They're as well interesting and sometimes challenging for 18 wheel travels and while being a wee bit slower than Interstates, they're actually to some (like me) SAFER.
ANY time I had or have a chance to run Back roads, I did/do it with glee whether in an 18 or 4 wheeler.
Not ALL back roads are to be taken in 18 wheelers and we that know know which ones and in which States.