Why not have something reasonable, and pay just the sum for given part of the year? So if vehicle spent 120 days at X, pay (120/365)xSUM, and the other place pays the rest (or X Y places).

Thats primary school level of math that in 2026 would be trivial yo implement, if fairness is the goal. We have such thing in Switzerland, you dont pay flat yearly fees/taxes/insurances if you register your car in december for example