Hello! Welcome to our forum.
Great idea, and one that has come up before! I am sure that at least part of your idea is covered by one of these:
Or do you mean real-world traffic? Because what FSTL is doing is likely not legal, and doing it the honest way would likely cost a fortune, unfortunately. However, if real traffic is what you are looking for, then the AI Traffic topic linked above should fulfill your needs.
Kind Regards,
Malte