I think we can make it work if we really wanted to without traveling, especially in SoCal.
Have SD, Galaxy, LAFC play top ECNL and MLS Next teams from SoCal.
For 2012s as an example, it would be Strikers, Legends, FCGS, Sporting CA, SD Surf, Albion Riverside, TFA, Pats, Beach, City SC, etc.
You can have a group of ~15 teams at a very high level that comprises of 3 MLS academies + 5-6 top MLSN teams + 5-6 top ECNL teams.
Play home and away and that's ~30 very competitive matches all within an hour or two at most driving.