I would guess any state that has 2 P5 schools like Iowa / Iowa St or Wash / Was St at least has the in-state rivalry thing going.
So my guess is it should be a school that comes from a state with just 1 P5 school. Potential candidates
Mizzou, Minny, Wiscy, Neb, nope they got out of state rivals
Utah, nope they got BYU
Colorado, maybe
Rutgers, maybe
MD, maybe
Arky, maybe
LSU, nope
BC, maybe