How about a a Celtic Club Cup made up of all Scottish Premier sides, plus selected sides from R Ireland, N Ireland, Wales, Brittany, Cornwall, the Isle of Man, Yorkshire, Northumbria, and Cumbria?
This would be a great trophy for Scottish sides to expand their market, and play big sides from outside of Scotland and it would allow the small sides from the two Irish Leagues and Wales and Cornwall to grow.
By the way this would be a group stage cup trophy on top of domestic leagues, and UEFA Club trophies.
The Scots have been allowed to have Irish, Welsh, and English sides in the Scottish Challenge Cup for a few years so UEFA would be fine.
I want to keep the Scottish League but have more cross border trophies.