I’m not sure what the best answer is but do believe that heavier vehicles should bear a higher burden of the costs as they have the most impact on the roads! However, I believe that everyone should pay something to have “some skin in the game”.
It pretty much works that way with Dino powered vehicles. Bigger and heavier have lower MPG. My 7600# F350 Diesel gets about 13-14 around town compared to my old 2100# Toyota Echo that gets 35-40.
EVs however are fairly heavy for their size. A Honda Accord has a factory spec curb weight of 3150#. A Tesla model 3 shows as 3582# or 4065# for either a single or dual motor. The Model S is up to 4766# and the X shows 5390#. By comparison an AWD Ford Explorer is 4437#. Going up in size, a 4x4 Chevy Tahoe lists a 5553# curb weight.
Those who have driven a Tesla also know the things are wicked quick accelerating too. This, along with the heavier weight, causes more wear and tear on road surfaces.
So if it’s about paying a fair share, EVs should pay higher per mileage road tax/fee.