Other thing I can agree but not the stability. RT and Legitimacy is not supposed to be low!! With Republic, you can "borrow" MP (keep the same leader) in difficult or early time and return that later. You are never short of Adm MP like in Monarchy. If you need a major increase of stab, then you need to restore RT first! And you didn't have the -1 stab when your ruler die!
RT should never be a problem, unlike legitimacy you have the power to control the RT! If you do it as a good stateman then you should keep it as high as possible but not to waste it when it reach 100!
How can you say you can control RT? There is no way at all in the hands of a player to do it - ways that are available for monarchies, instead.