Apologies if you've tried this and it isn't what you're looking for, but my first inclination would be to set the beats to switch at the end of the bar or something similar? That might offer a solution.
Another option could be to integrate some kind of foot pedal that you can set to particular MIDI notes associated with whichever pads you have your beats on. I have not tried this, but IIRC there is an option to have an external controller switch beats.