Very few, if any, modifications are going to dramatically change a vehicle's curb weight. Of course, electrics weigh more than similar ICEs, so a better reason to skip a weight based tax is so as to not disincentivize electrics.
Edit: Also, what do you mean "rice burners"? Afaik, rice burner refers to any vehicle of Asian origin whether tuned or not. And trust me, tuning a car is not going to increase the curb weight by more than a few pounds.
Do you think an electric car that weighs 1000lbs more than similar ICE cars is doing that much more damage to the road? And compare the damage cars, suvs, etc, would do versus box trucks, tractor-trailers, etc. There is no comparison to the damages between the two classes of vehicles. While true, an SUV will do more damage to the road than an econobox hatchback, even combined they don't equal the damage a fully loaded tractor-trailer will do.