Gambatte, I empathise with you and salute your self awareness and honesty. There is another option not yet mentioned.
You have said you a super-specialised skill set in a rarified research environment. You also love what you do, its just the contractual obligations that are killing you.Your skills and talents are therefore;
1. Highly valued.
2. Exceptionally rare.
3. Probably mission critical.
4. Unlikely to be easily replaced.

You need to take stock and realise that you have a strong hand of cards. This should allow you to take a brave step. Resign from your employed position and contract yourself back on your terms.
I have a cousin who has done this for years within the oil industry. He is one of the few people in the world that knows how to drill sideways. He has spent time both as an employee and a contractor to the same company so I have observed that this quite possible.

So my advice to you? Take control of your life and become self employed. It may seem scary but, if you are good, it could work. The worst outcome that they don't hire you is not that bad if you are already thinking of leaving.