Err I don't think that Generals have a significant influence on that. In my Romani campaign I changed the trait file to delete the Impostor-trait and the EDB to make it possible to recruit Client Rulers outside of Italy (all governments except the Italien one). Except for Italy, Sicily, Corsica and Sardinia all provinces (i have a total of 38-40) are ruled by Client Rulers and I have 3-4 Generals moving around. Though, I have more then 20 FMs, more to come of age and my female FMs still get marriage proposals.