You have a few options here.
The M5 CS can be financed through "BMW Select", which has a much lower payment, and a balloon payment after 5 years.
Given the perceived value of this car, you can easily resell it and pay off the balance of that loan after 3 years. (you might even make some money)
You can also find a third party to do the lease (such as
https://www.amazonleasing.com/), or contact @Ex Stig to see what company he used.