Judge-based Sharia law, where we divide Somalia into different local regions and rotate judges into each area, with them choosing a first among equals to be the head of state.
Confederalism is pretty much like a friends-with-benefits type of relationship. If Somalia balkanizes, anyone who believes that those smaller states will somehow unite in an EU-style deal is delusional, simply because border disputes are going to be a day-one issue and wherever you draw the line, someone’s going to be angry.
Any type of democratic system needs to be coded against tribalism. I’d probably implement single transferable votes for the presidency, so the election is won by the candidate we collectively agree is the least bad option. Parliament would need a two-thirds majority to pass anything, simply to make it impossible for two clans to monopolize power.
I’d probably make the Somali Supreme Court the last vestige of 4.5 and give it veto power over any legislation only if it has the explicit and intended effect of disadvantaging any specific Somali community based on tribal characteristics. This could include anything from building coal power plants exclusively in Jeraarweyne areas to disproportionate investment in certain regions, etc.
By wanting to eliminate tribalism, you often end up reinforcing it. You can either delude yourself into tribal colorblindness, or we can craft our system to deal with it directly.