I can confirm that bass crumhorns certainly existed, and there are even some museum examples of them! (in Munich, for example). Praetorius's extensive manual on the instruments of his era (first decade of C17th) lists not only a bass crumhorn, but also a "great-bass", pitched a fifth below the bass crumhorn. He also provides illustrations of the complete set. I've played both the bass and great-bass crumhorn, and even got involved in constructing a modern reproduction of a bass crumhorn (which still plays, and can occassionally be seen in action at the Globe Theatre in London). There's only one surviving piece specifically intended for crumhorn consort, which is a single "Paduan" (ie Pavane) "fuer Krummhornen" by Praetorius's contemporary, Schein. It's a stately and funereal piece that's unusual expansive and expressive for such ungainly instruments ;-)
If you think a consort of crumhorns is comical, wait until you see (and hear) a consort of racketts