I'm sure Genghis will refer you to the various threads about test pilot training.
The answer, I hope, is yes!
The golden age of many companies producing endless prototypes competing to meet military and civil specifications is long gone. Sadly. Most of us earn our living from development of existing platforms and a bit of research.
In the helicopter world there's lots of exciting systems work, primarily militarily driven, to develop day/night and all weather operations, for example.
It has to be said that companies generally prefer their tps to have come from the military background so that they have the necessary 'role experience' to encompass a broad spectrum of flight test activities. It is 'role relation' that is the crux of the tps job in declaring the suitability of an aircraft or system for its purpose, and he (/she!) must have credible role experience to do this.
Joining a smaller company as a FTE (with your aero eng background) might enable you to get a foot in the door and eventually transfer these skills to the pilot's seat. Our good friend Genghis will attest to this!