> 4. Dual license it as GPL and commercial and: This works if your product can target big corporations. They are unlikely to intentionally misuse the license;

> 4. Dual license it as GPL and commercial and: This works if your product can target big corporations. They are unlikely to intentionally misuse the license; and would pay licensing fees for something that can be freely available online. There are several companies doing this already. You just need a few contracts to cover a software engineer salary. So unless you are after maximizing profits, you don't really care about the dudes who are using it commercially for free.