If we expanded the minor league roster then I would prefer to see two minor league rosters. One could be AA-AAA and the other could be R-A-A+. There could be fancier names or even simple names such as High-A and Low-A. My thought is that the Low-A roster could be treated like the original EDR with the exception that players acquired via trade from another Low-A roster can go to the new team's Low-A roster. Otherwise, a player must be drafted by that franchise in order to be on the Low-A roster. Promoting to High-A roster would be necessitated to clear room on the Low-A roster. That can be viewed as surviving the cut and process of going through the minor league system. Now, the High-A roster and 40-man roster could also have some new rules that could impact player options/waivers and a Rule 5 draft.
The goal of this league is to be fun, free, and realistic. Being truly realistic with absurdly sized minor league rosters of 80+ players seems to be too much. Maybe this idea could be a blend between realism and bring something to a ProFSL baseball league that has not been seen elsewhere.