On the hard coding part, OOTP doesn't enforce roster limits int he minor, it just shows as cosmetic, however fi you have the AI organise your minors it will try to organise them as best as possible within the limits, but it won't release players. That has to be done by the commish or the GM.
Troy - just a quick point, having that many players is actually a disadvantage in their development (i.e. you're less likely to get that 1* turn into a 4-5*), as one of the keys to development in OOTP is giving your players playing time in the minors, so having 20 SPs on a minor league roster when you can only start a maximum of 6 is of no benefit to you or the players, whereas the league could benefit, and enhance player movement by these players (or others instead) being in the minors of teams where they can play.