. I had a job interview today at an aerospace research institute
If you can get it grab it.
Simulation is becoming more and more important in all aspects of aviation and that includes flight test. The different approach required by research (and experience of that) would be excellent CV stuff for any FT position anywhere.
Various organisations use in-flight simulation because the real world and motion cues are of course 100% correct which greatly reduces the doubt about the overall validity of the tests.
I agree with FTE Pruner about a PPL but don't waste money going further.
Once you have a feel for what you are talking about regarding the research uses of simulation and believe you have experience and motivation to offer in that field, start writing to research organisations with your views and case for how you could help them. We know if you don't ask you don't get but there is much more to a FT job at this stage of aviation history than just asking. You have to keep asking and keep making the case for what you have to offer. Make sure you know all that is in the public domain about the projects of the organisations you approach and taylor your comments to how you could help them with XXX.
I am interested in your choice of Flutter speed as a handle. When I was young and at the peak of my FT career there were only two tests that I would not do without help. One was flutter and the other spinning. PM me with an email adress and I will explain why. With anything else I felt competent to write my own flight test programme that would get the required data and not risk the aircraft.
I think if you have enough experience of and thoughts about the use of simulation in research, you are well on the way to a job at (say) the likes of Calspan.
In your position I feel you should build your FT niche round simulation. Be determined to be the best in the world at the use of simulation in R&D and FT and you will make yourself the man to hire.