My thoughts are there is 18 teams in both the Premiership and Championship.
Southern: Somerset, Swindon, Ipswich, Kings Lynn, Wolves, Peterborough, Poole, Leicester, and Rye House would compete in the Southern half.
Northern: Glasgow, Edinburgh, Berwick, Newcastle, Workington, Redcar, Scunthorpe, Belle Vue, and Sheffield would compete in the Northern half.
Number of riders could be an issue, but if the average for team building was raised slightly this could possibly accommodate more riders (possibly not as well). Yes costs also would increase with this, but that would have to be a calculated business decision which hopefully would prove a success.
Please remember something has to be done quick, as speedway supporters at the moment are rapidly dwindling and so will the sport if a remedy cannot be found soon.