How about having the President and the PM be from opposite religions? Have a Muslim President appoint a Christian PM and vis versa. The Speaker of the Parliament and the Speaker of the Senate will be from sects not represented in the first 2 posts, one will be Muslim and the other will be Christian.
Salvation from what? Sectarianism? Eliminating sectarianism will not take place through administrative and institutional reform. Confessionalism is rooted in the very foundation of this divinely forsaken country. It's part of every story you hear about the country's existence (the Antelias declaration, Fakhreddine's myth, and the like).
Western secularism is a far cry from anything Lebanon could ever achieve. Secularism exists in Western societies like the US and Canada thanks to a history of practices that provided the structural foundations for such a system. Before that happens in Lebanon, expect to see a continuation of the same trite sect-protectionist discourse and political manifestions of today. Political parties will not cease to appeal to sectarian agitations just because the system doesn't allocate power according to religion.