“If still tied, the representative will be the team that has not participated in the championship game most recently.” Southern Miss (2015) would win that tie-breaker ahead of Louisiana Tech (2016) and UAB (2018).
https://cusareport.com/2019/11/24/2019-tie-break-scenarios/
https://cusareport.com/2019/11/24/2019-tie-break-scenarios/