No separate division for the G5. That would regulate the G5 to a pseudo FCS.
What needs to happen is the G5 to force solidarity with the P5 - a more level playoff scenario:
Solution 1 (compromise): 8 team playoff: 5 P5 Conf Champs, 1 G5 Conf Champ (highest ranked), and 2 wild card spots
Solution 2 (unity): 10 team playoff: All FBS Conf Champs would be set into a post-season. Seeding according to rank.
To get to Solution 2, we need to at least make it to solution 1.