I was looking for a way to make a kit combining a Coat-of-plates and a hounskull. Coat-of-plates seem to have been popular in the Germanic-region until relatively late, though I'm not sure how often the hounskull was used there. Does anyone know this?

Depends how you are using hounskull. If you mean the pointed face visor then yes later in the century it was in use in Germany. Keep in mind that in theory and in trade what would become Germany and Italy were in the HRE. The best way to get familiar with the armour is artwork for style and design.

RPM