That's a very good question.
I would imagine that with the bigger "collective" deals, there is a greater chance of solid legal review, at least on ONE side (maybe not as much on the player side). For smaller "autograph signing" deals, little one-offs, I don't think there is much scrutiny at all. For a larger "Dr. Pepper" deal with a large publicly-traded corporation, I'm sure there is a whole legal team that has reviewed the deal on the corporate side.
If there will be a "Clearinghouse", then the smartest possible thing to do would be to create a special template. In it, you would include:
A. Standard language that should govern ALL of the NIL deals, such as the language above about "not compromising eligibility" and approved language on "needing to be geographically available to perform such services".
B. There should be a clear "fill-in-the-blanks" recitation of payments to be made and services to be performed.
C. Finally, there should be an "additional clauses" section, where you could insert anything unique or unusual to the contract, and THIS is the stuff that Deloitte would really need to scrutinize (actually, lawyers would need to do that, as Deloitte US is just an accounting firm, while in other countries Deloitte can provide legal services).