FBS future schedules has a list of who still needs an opponent. There are 12 of us out there in FBS currently in need.
https://fbschedules.com/fbs-college-football-teams-with-n... /
Baylor (likely FCS opponent)
Jacksonville St. (likely FCS opponent)
Louisiana
Miami Fl (likely FCS. They already have Fiami this year)
Ohio
Sam Houston (likely FCS)
San Diego St.
SMU (likely FCS)
Southern Miss (Alcorn St?)
Tulane (Nichols St?)
That leaves SDSU and ULL open for an FBS opponent. ULL however could use a 6th home game while SDSU already has 6 home games. A trip to San Diego would be nice for recruiting and an instant TV game on CBS Sports. A series with SMU would also fit the bill and good for recruiting.