• Is there a small Midi footswitch that can send preset up/down CC messages to multiple H9 pedals? (A separate up and down switch for each pedal and reliable for stage?

Based on your description, I think the most simple and room saving solution is to use Ox9 on the first H9 to increment/decrement and load presets, and use short MIDI cables to connect to 2nd and 3rd H9s. The 1st H9 can send MIDI messages to also increment/decrement 2nd and 3rd H9s when you press the footswitches on Ox9.