Another option with a flex week is to let the teams decide starting at the top of the pecking order. They can choose to either host a game or else challenge a higher ranked team as a road team.
So Oregon as #1 gets to host a game. PSU #2 then can choose to either be a host for a game, or challenge by traveling to Oregon. So let's say PSU chooses to host.
Next Indiana #3, gets a choice to host, or travel to Oregon, or travel to PSU. Indiana chooses to travel to Oregon.
Next Ohio St at # 4, can either host or travel to PSU. OSU chooses to host.
Next Iowa at #5, can either host or travel to PSU or OSU. Iowa chooses to host.
Next Illinois at #6, Illinois chooses to travel to Iowa
And so on, until you have 9 teams hosting, then the remaining teams have to choose to travel.
Of course, maybe there would need to be some rules in place to make sure there are no rematches and you can't choose somebody more than 3 spots above or below you in the rankings.