Doombunny,
Is there any chance of you considering a mod that just changes the vanilla drummers to bearskins or cocked hats?
Generally only grenadier and fusilier officers wore grenadier caps and often even they wore cocked hats so you wouldn't really ever see officers in bearskin caps unless they were commanding grenadiers or fusiliers who were also wearing them. Drummers on the other hand would wear bearskin caps even in the "hat" companies.