The Butterfly Effect - Priorities

I consistently run into an issue in the late game where I have been at my vehicle cap for quite a while, and balancing truck tasking via priority assignment becomes impossible to manage. As an example, my steel production went to zero due to limestone no longer being delivered which I responded to by bumping the priority of the storage bin from 9 to 8. The effect of that change was that virtually all food delivery to my settlement ceased. I am faced with spending my entire play time managing trivial logistics details. I am not sure what the solution is, but elimination of the truck/vehicle cap would be the simplest fix I believe.
This map Is Dragontail Isle, year 611, 200 vehicles.

The solution is belts. Or perhaps trains. But you should switch away from moving high volume goods like food by truck.

Vehicles are CPU intensive, so the cap is there really to protect you. You can assign trucks to storages which enforces to have always something moving it (from or to). You can also try to replace some trucks with theirs big variants (those should be always assigned to not try to go where they cannot). But you should either replace some of them with belts or trains (Dragontail is designed for trains) or slow-down your consumption by slowing research or making construction parts, by lowering your population or by using edicts like vehicle overloading, fuel saving, food saving, maintenance reducing.
Also the diesel demand can go very high with that amount of vehicles, which could lead to other problems soon.