Maybe Midi Solutions pedal or footswitch controller? Both can be programmed to transmit sysex messages via pedal activation.
You can only do one command of sysEx with these two if I remember correctly. Their Event Processor Plus, which I have, can handle multiple strings of sysEx messages.
I might add that with the EP+, still you need a MIDI foot controller with multiple footswtiches like the FCB 1010 to trigger each string of sysEx. Unless a person already has the EP+, the whole setup gets up a little too expensive and complex.