Even after sleeping on it, I really like that "1+X/4" playoff where the tournament telescopes up or down to a maximum size of 5 teams, determined entirely by the quality of the field that year (the system would include some objective cut off for exclusion, like 3+ losses), only conference champions, no substitutions.
"3 or 4+ losses" are an imperfect cutoff as we've discussed, but it's the first cutoff we've mentioned that ignore committees and polls.
1+X/4 could easily incorporate a better cut off if we could come up with one.