You can do it through materials, though it would be a challenge to put together the exact math you need. However, I did some further digging and found out that from our support team has put together an awesome wiki tutorial on doing something very similar to what you are trying. Take a look here and see if you can utilize the information present:
What is good is that he uses instanced meshes in his scaling, which means that the draw calls will be extremely low for what you are trying to do.