We just need to have all HS students who intend to participate in Intercollegiate Sports take an AAT - Athletic Aptitude Test.
Besides collecting physical and mental test results, AAT would also assign minimum and maximum dollar value to each student-athlete, and schools would not be allowed to pay more than maximum nor less than minimum. Test scores and valuations would be publicly available.
To maintain scholastic standards, schools would be required to deduct all of its normal student tuition and all other fees from the amounts paid to each student-athlete. No more "scholarships" for athletes, just real educational benefits like every other student. This might affect expensive schools negatively, but that only serves to level the playing fields.
Straight NIL would probably belong to the employer, the school, but not necessarily exclusively - actual name/image/likeness payments could be split between school and athlete, and non-NIL employment (ditch-digging, vinyl siding sales, etc) would be none of the school's business other than any restrictions on all students in general.
And, best of all, Deloitte could be entrusted with the AAT.