Tempo Trainer waltz?
I noticed in Danny Dreyer's latest book that he suggests using the Seiko metronome (the running version of the Tempo Trainer) on every third stroke, rather than every other -- the idea being to avoid emphasizing one leg over the other. So in swimming, this would be "beep-2-3-beep-2-3", left arm-right arm, and so on. I haven't worked out the math for the TT, but it works very well for Chi Running. Worth a try?