This does sound like an interesting idea that would open our platform up to people with lower end PCs. I’m not sure how this would be implemented, though, Maybe an option to reduce players vehicles to simplified traffic cars on your instance of the game? I feel like all of the major set pieces are already there to make this work. We have a simplified traffic vehicles already, and ghosting is already possible as shown in RM2, we also know that client side modding is possible.
Someone just needs to figure out how to get all of those functions to work together. I encourage and invite somebody to try, if you get it working, we might even be able to add it to the base platform and give you a contributor credit!