Have you considered a dual band compressor effect?  As a bass player I like to apply different compression to high & low frequencies so I don't lose as much dynamic range as I do with full frequency compression.  I think this could also work if you could assign different effects to the left & right signal paths?
I just found this app, I was trying to use Amplitube before, but this app is Fabulous!  I love the compressor - control of all parameters!
Keep up the great work!

Dan