There are no maps in which the focus is the HRE, so an ideal map is going to be impossible unless you make one from a scratch.
Ollie's 30 Years War map has a decently-detailed map of it; subpar for your goal, but better than sticking to nothing; you'll struggle from having 2 to 5 territory nations often, though.:
https://www.warlight.net/Map/17567-Thirty-Years-War-16181648