If it was an "Ideal" SL where everything is great/clubs are self-sustaining etc then I'd have a 16 team league of:
Leeds
Wigan
Huddersfield
Bradford
Sheffield
Hull FC
Hull KR
Saints
Warrington
Salford/Manchester
London Broncos
London Skolars
Nottingham
Gloucester
Newcastle
Wrexham
Similar to NRL where top 8 play each other twice and bottom 8 once (and vice versa for bottom
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with a top 8 playoff. Obviously Challenge Cup.
3 overseas players allowed per club.
A Heritage round, plus a "youth" round where at least 8 players out of the 17 must be non-overseas and under the age of 24.
a 3-game series Origin Series consisting of Yorkshire, Lancashire & Rest of UK/Barbarians type side. The previous years winner is automatically in the next years series. The other participant decided by a preliminary game.
A mid-season Tri-Nations between England, France & Wales. 1 game each followed by Final.
Every 2 years there should be an end of year 3-Test Series rotating between GB, Australia & NZ. With a World Cup every 4 years.
Oh and as its an "ideal", there would be P&R re-introduced as the Championship would be strong enough ideally.
If its working with what we've already got then a 14 team league is about right, as are the teams within it.
I'd like Magic Weekend to be at Etihad permanently and built on, and also have the Magic Weekend be a Heritage Round.
The Challenge Cup should start later so there is more momentum built in it going toward the final (ie not such big gaps) plus restricted to only 1 overseas player.
I'd also replace the Exiles game with a 3-game Yorkshire v Lancashire series.
And restrict those picked in England/GB/Elite squads to playing 24 regular SL rounds & 3 CC games (not including the final).
I'd be desperately trying to find a very rich owner to take over London Broncos.