Paul,
I think you can do a lot of cool things just playing an octave of short pedals, even just using the toes of your left foot.
You could practice walking a bass line with your left hand while tapping a note on the pedals to give you a thump.
Write out a two-beat jazz bass line where your left hand and left foot played the bass line in unison.
Practice a bass line for a slow song where you play the bass line with your feet, chords with one hand, and melody with the other.
Practice scales or scale fragments, making the scale legato just with the toes of your left foot. Difficult at first, but totally possible.
Practicing scales, start on the lowest possible note on the pedals and go up. So if you're practicing an Ab major scale, you'd go low C, Db, Eb, F, G, Ab etc.
I have the XPK-200L pedals, and I think they're pretty good for a portable compact set of pedals. I'm sure the Rolands you have are excellent. There's an organist I've seen a few times around here who has them, and he does a ton of great music using the one octave.
Good luck,
Doug