The SPL came about for the simple reason that Rangers and Celtic wanted to play each other as often as possible every season. They milked that dry and so the newer formats were created. They continue to milk the current format dry and the other clubs just bend over and take it.
I'm not sure why you think there is quick fix. When a situation is allowed to develop over a number of years, and some of its participants have facilitated the decline, the fix is not likely to be anything other than a longer term process.
Some ideas (which are hardly radical) might include:
1) Getting rid of the man who can't find a sponsor for the league and who is on record as saying it doesn't concern him.
2) Bringing in someone who can get a sponsor for the league.
3) Bringing in someone who talks the game up and markets it properly instead of talking it down, and broadcasting doom and gloom about the lack of Rangers.
4) Splitting the league revenues more equitably between teams.
5) Stop messing around with schedules so fans can plan to attend games.
6) Get rid of the split in the league
7) Related to 6), stop playing the same teams so often
8. Getting a winter break in.
What in reality is going to happen is that, once Rangers are back in the top flight, magically a league sponsor will appear and 90% of the money will be sent directly to the OF. They will continue to take an unfair share and more clubs will end up going to the wall. And everybody will be afraid to vote against the OF because half the chairmen in the country are fans of one side or the other, and the other half only care about the short term viability of their club - not the long term viability of the game.