I like what you are saying, but you can simplify it to making "Holy Rman Emperor" a Titular title that has no vassals and making the title of HRE electable by DeJure Dukes of the Empire (or primogeniture via an expensive decision). However, the holder of the titular HRE is permanently allied to all independent entities in the Empire de jure, and based on your relationship with them, you can call them to your wars. I really wish I was capable of modding that.[/QUOTE
You see, I don't necessarily think that's needed. The idea of the HRE as a territorial state shouldn't be excluded - if the HRE isn't made titular, a successful dynasty of Emperors could build up a large enough state if they maintained good relations, although it would be vulnerable every time there was a bad succession. With luck, planning and skill I don't have a problem with the Emperor attaining direct control of the de jure territory of the Empire. He just shouldn't -start- with it, and the accompaniny critical mass of troops that makes all but the most catastrophic rebellions stillborn and all neighbouring pagans steamroller fodder.