Maybe I don't understand how bad your roads are. I used to live in the mountains and had to drive 2 miles up a dirt road to my home. It would get potholes in the winter and wet season but I learned to avoid most and sit so that I could tolerate the rest. Even the paved road was full of potholes but we learned to avoid them or slow down.

Understanding the physiological mechanism behind the sensitivity would be interesting but not help unless there was a treatment to resolve the sensitivity. As with the rest of PCS, treatment is just not available.