So here's my first attempt as Saxony. The first 50-100 years or so went on slowly when I spend most of the time minting and changing the sliders towards free trade and plutocracy. Took my chances at making Salzburg and Genoa my vassals by attacking their ally Venezia that was excommunicated and after that it just kept rolling I was the emperor until the 1760's and then disbanded the HRE. Should have disbanded it earlier though, then I wouldnt have suffered so much from infamy penalties.
All settings was set on default except random lucky nations. Difficulty normal.
Just a little edit.. I have not released/annexed vassals to lower my infamy.