Yep. I know I've banged this drum before, but I can see it switching to two conferences of 7 teams. Play Home & away gainst every team in your conference (12 games) Home OR away against every team in the other conference. Draw up the conferences so you can have a final cross-conference derby round (If we're in Conf A, put Sarries in Conf B. If we played them at home in the rest of the season, we play away in the derby round) That's another 8 fixtures with everyone guaranteed to have the same number of home regular season fixtures. Top 2 in each divisions standings qualify for the Semis. Conf A winner plays Conf B runner up & vice versa, and the Final adds another 2 weeks so the whole season is covered in 22 weeks, 2 less than it was prior to expansion.
Is it ideal? No. But it means every team plays every other team at least once. Every club has the same number of home fixtures (admittedly 10 rather than 11 or 12), and you actually free up a couple of w/es that are currently used.
Not sure about the idea of Derbies. Mainly because I’d guess Sale’s would be Newcastle (150 miles/2hr 41mins) rather than Wasps (102 miles/1hr 45 mins).
That said, the unintended consequence is that indirectly for this plan it makes more sense for Ealing to come up and for ring fencing:
Sale v Falcons - Northern Derby
Tigers v Saints - East Mids Derby
Worcester v Wasps - West Mids Derby
Bristol v Exeter - M5 Derby
Bath v Gloucester - SW Derby
Irish v Ealing - West London Derby
Sarries v Quins - London Derby
Swap Ealing for Pirates or Doncaster and it starts to fall apart a bit.