I have thought about this and it has been discussed on other forums. I think a sub XX waiver and over XX waiver would be a good option. I think you will get more of a response than the turboprop waiver because honestly, turboprops are cool but I don't see a lot of people starting there, no waiver, due to the fact they actually cost more to enter.
Your boomerang example is valid. Here is my go to example of a legal waiver flight plane that prepares you for pretty much nothing other than how to operate a turbine.
Again, with the proliferation of the smaller turbines, there has to be a way to welcome those who want to enter jets on a smaller scale. The people I know that would get a smaller turbine to start if they wanted to go bigger later would have no issue with getting another waiver when the time comes.