Another few thoughts:
- If you are working for them, they are legally bound to pay national minimum wage at-least.
- If you aren't working for them, nobody: you or they, are protected if anything goes wrong.
I think you'd be better off haggling a badly paid fixed term employment contract, with a review to a decent wage, or a polite goodbye (but they got somebody to fly their aeroplanes cheaply, and you got the hours, experience and a reference) at the end of, say, 6 months.
G