So it turns out you can control the Boss RC-5 looper pedal via MIDI instead of needing to lean down awkwardly to adjust the built-in drum machine, so I bought an (Australian-designed) MIDI controller, the Pirate MIDI Bridge4! It's pretty slick, but unfortunately Boss' documentation on how specifically to configure external MIDI devices to control it is a little lacking, so there's a LOT of trial and error going on right now.