that is a really interesting idea kelt. It will never fly under the current rules cos as you say the old firm would not have their CL carrot and would therefore stand together and veto it. east coast league sounds pretty good as your pretty much getting the best of the spl outwith the gruesome twosome. West coast league sounds shite though. OF, falkirk, st mirren, killie, minkerwell, hamilton, morton, partick and ayr. would be boring as hell.
I think the most realistic improvement would be a 16 team league so teams only playing each other twice. 20 is unfeasable as there would be no one left in the lower leagues capable of the step up. the league cup would have to be revamped, perhaps into a sort of champions league format, so as to make up the missing revenue from losing 7 league games.