Me too. Let the Cinderella thing happen organically through that model (ie with an unexpected conference champion) rather than try to force it by automatically adding Memphis or UCF or Cincinnati each year.
10000% you do this but I don't necessarily give the Group of 5 that auto bid. Lean toward just 3 at-large spots. Or at least mandate that the Group of 5 has to be a top 10 or 15 team.