I'd expect Broncos would end up doing what the League One southern teams do/did and have some players living and training up north, travelling for matches. They will probably all live close to each other for ease of training and travel. Where would depend on the coach and his contacts.
Oxford spent two years with half the squad from the Leigh area and three with half the squad from the Castleford area it's not exactly ideal but I can't nsee how they can pull together a Championship standard side using only southern based players