I commonly play with a five-string capo on the second fret of the guitar, leaving the E string open. This only becomes a problem when attempting to play an F# chord with the bass note:
As you can see, it's hard to get my thumb in there to fret that F# bass note, particularly on this narrow neck. (It's easier on my dreadnought guitar.)
Is there a better way to do this? Perhaps there are better capos for this purpose? Is my technique off? Should I get started on growing that third hand?