My job entails me having a limited company and renting myself out to other firms. I am always offered either a flat salary, or an hourly rate. I always take the hourly rate. The salary is usually higher on paper, but if you're dumb enough to sign up for legal slavery because you're greedy and can't think ahead, you're really breaking my heart.
Every one of the people asking for OT pay knew that was not how their contract (a legal document BTW) worked. And now they're finding out that being stupid and greedy has consequences. Oh, well.
Way back and in England, I worked in IT as a "contractor" and had to create a company because the Inland Revenue (tax) people wouldn't allow a self employed status, due to abuses in other areas of work. I never had any option but hourly pay, and that was fine. The company gave me options to deduct various expenses, and give myself a company car, but I was also subject to company taxation like the equivalent of FICA here. There was a constant game of ping pong going on between the Revenue and my accountant, to minimize this. Do you have the same problem?
I've never worked in that way since I moved to the USA 36 years ago. One (non contract) job I had in England delimited salaried employees by amount earned and I was the only one on that basis in my department because as the latest to be employed I made a small amount more than the others and it pushed me over the edge. We were all doing the same job. Note that the sum was reasonable to separate "management" from "workers" generally, but we were paid a lot more for market reasons. It took me a while to work out that when we were asked to work a lot of overtime I was the only one not being paid for it. Today I would protest, and if I didn't get a change I would either refuse overtime or move on. Then, I put up with it.
When I first started work in the US I was amazed at how people would work long hours and only be paid for the first 40. I predicted that the employers would eventually run out of the good will that enabled them to exploit workers to that extent. I think it has happened somewhat.