What this shows is that we need a pyramid! There's no point re-creating the Connacht Senior League, so lump them in with Ulster. MSL needs to be expanded to cover all of Munster. The existing Junior Leagues can feed into these.
Is there currently prize money on offer in the LSL or MSL?
As regards B teams playing in a pyramid system, maybe allow them play up as far as the third tier. U-23 leagues are a waste of time imo, loan younger lads to teams further down the pyramid and at least they'll have experience of playing mens competitive football.