5-7 Missouri will not accept a bowl bid. They were the #2 APR team (tied with K-State, actually). So K-State is in (assuming they accept) regardless of the outcome of their game Saturday.
One thing that I'm not clear on is whether 5-7 teams will be able to fill a conference's bid as though they were 6-6. Specifically, in the B1G, there aren't enough teams to fill all their slots, so the Quick Lane should open to the MAC. But if Nebraska, Minnesota, and Illinois all qualify due to APR, can the B1G fill the Quick Lane bowl with one of them, or does the MAC keep the spot?
(My guess is the B1G will get it's way, whatever works best for them, because that's how the sport is run.)
A hunch tells me just answered your own question. I bet in every scenario the G5's get screwed.
I don't think they'll be allowed to backfill with 5-7 teams as if they were 6-6. One option I've heard is that conferences would be allowed to backfill with 5-7 teams after all bowl eligible teams have gotten a spot. So if there are five openings left and two of them are B10 slots, B10 teams could be named to fill them. I'm not sure how it would work with individual bowls; B10 has its bowls in three tiers, with the bottom tier this year being Quick Lane and Armed Forces.