I heard AD BM on the radio Wednesday night where he actually mention this, IRCC he used the term "squad list", I would say "roster spot". I think Title IX is worded something like " athletic opportunities" so roster spots would count no matter whether financial aid is involved. I do recall that roster spots do not have to be equal but must match the male/female ratio in the general student population. Which actually is creating a problem because because more and more women are going to college and the ratio is constantly changing in favor of the women. I am going to actually count the number of people on the roster of the various teams and see what we have. For example there are more than 50 women listed on the track and field team.
Personally, I think 45-50 walk-on's would be ideal. They would mainly be practice fodder, but it would allow the players on the three deep, the ones who would play on Saturday, to get live reps against people while running their offense/defense. During the fall your time is spent getting ready for your next opponent. Breaking down the numbers, 85 scholarships, four deep offense and defense. The 4's are the practice squad. They provide the opponent's plays and defensive looks for the 1's. Without more walk-on's the 3's have to play the opponent's for the 2's therefore the 3's get no reps of our plays and sets or if the switch roles they get half of the 2's reps. With 20 more walk-on's the 2's have their own practice squad and the 3's stand around therefore, 45-50 walk-on's would be ideal. When I say live reps I don't mean "tackle to the ground" just cases where you need opponents that run and react to what you are doing.
Husker56 beat me to the post. Some good info there.