It all depends on the people you are dealing with and your own attitude. I did excactly what youre planning to do about 25 years ago in Germany. We did end up in court and I won so he had to pay the court costs as well and I didnt have to pay any rent for nearly 2 years.
I would sit down and do the whole deal in writing. Including all the numbers and most importantly what you think you should get paid per hr.
If I was doing it again I would rather pay the standard rent and send the owner a bill from time to time so everybody knows whats going on.
You could even quote each job and get the ok before starting.
I wish you luck and try to use your head more than your heart.
Cheers
Reiner