I think 12 is to many, 8 would be best. If they go to 16/24 they could have teams with as many as 4-5 loses, plus attendance would be hurt depending on locations and weather.
This really isn't valid concern for a 16 team playoff, especially for a 5 loss team to make it. This year no 4 or 5 loss team would be in with 16 and only 1 would have gotten in with 4 losses (Iowa at 23). Last year no 4 or 5 loss teams would have made in in even a 24 team playoff. In 2023, none in a 16 team, but 4 four loss teams, no 5 loss teams in a 24 teamer. In 2022, again, none in a 16 team, but 6 four loss teams in a 24 (including State at 22). In 2021, none in a 16 team and just 1 four loss team in a 24. So you are correct, some 4 team losses will make it in a 24 team playoff, but almost never in a 16. Not that a 4 could not make a 16 team, but it'd be very rare.
Interestingly without auto bides, in 2021, 2 G5 teams would have made it in a 24 team, but none in 16. In 2022, one G5 would have made both a 16 or a 24 teamer. In 2023, 1 G5 in a 24 but none in a 16 teamer. In 2024, 3 G5 teams make it a 24 team, but just one in a 16. And this year, none in a 16, but 2 in a 24 teamer. Take that what you will.