Chicago
I live near SeatGeek and have always thought it would be a perfect fit for spring football. There is a sports dome, turf fields that could be used by the team and a hotel 700 feet from the stadium. Hotel has 109 rooms and meeting space. SeatGeek is probably going to be vacant in a year or two when the NWSL's Chicago Red Stars relocate into the city.
SeatGeek also hosts high school football and was scheduled to host BYU vs Northern Illinois in 2020 (game was cancelled due to COVID) so they're 100% prepared for football.