There
is a reasonable amount of music written for bass clarinet.
There would have to be, considering that these days you can take a Masters degree in contemporary bass clarinet performance (at least in Holland).
You can also study it as a principal instrument in Australian high schools and they have a syllabus for it, I'll paste the recommended works here:
Year 11:
QUOTE
Bass Clarinet Typical Pieces
Gorman, Pastorale and Bourree, Rubank
Phillips. Recitative and Slow Dance, Rubank
Prokofiieff. Romance and Troika, Rubank
Spooner, O. Chalameau Sonata for Unaccompanied Bass Clarinet in the Low Register,
Southern Music Co
Unknown. The Foggy Dew - Old Irish Tune, Rubank
Year 12:
QUOTE
Bass Clarinet Typical Pieces
Boni Largo and Allegro, Rubank
Eccles Sonata in G minor for Bass Clarinet and Piano
Koepke The Buffoon, Rubank
Marcello Sonata in G major for Clarinet and Piano
Rhoads, W Ten Solo’s for Concert and Contest for Bass Clarinet and Piano,
by W Rhoads, Southern Music Co.
Tchaikowsky Sleeping Beauty, Rubank
Vinter, G Song and Dance for Clarinets and Piano
The Bass Clarinet is a fantastic instrument, good on you for taking up the challenge!