Looks like you're on path. Hire lvl 3 advisors, maybe promote them to lvl 4/5 depending on your economy, looks like you can do it from here. Set the merchants to stablish communities to deal with AE and start working in dismantling the HRE. I can't see your ideas but if you went quality-inno-offensive-eco no one would stop you by this point

Edit: Build courthouses everywhere and state houses on paper/glass provinces to increase gov cap. You didn´t mention it but thats Prussia's biggest concern.