How about not selling to these guys, period. I just have this feeling that once you take money from a Fortune company, you are their employee. Same goes for the government.
Customer/vendor is a very different relationship than employer/employee, even for consultants to say nothing of SaaS vendors. You don't have to run your vacation plans past them, you can moonlight at 10 jobs simultaneously without of running out of hours or having any of the jobs think this is odd, you can hire people to do the delivery in a way an employee cannot, you can sell your relationship, etc etc.
No lie: occasionally more stressful than working for W-2, and you largely don't get the option to just focus on delivery, but it's a very different beast.
[1] Never been in that position; have been in the "Oh, good, you're finally here. THE SKY IS FALLING!!!11!" position, though.
[2] Actually the clocks don't work that way. But I don't understand them anyway.