If you want to chain the units like this you have to set them up for MIDI THRU (so that they will pass incoming messages to their outputs).
This means that you cannot have any of the pedals generate an output. Meaning, that you can't use any of them as a MIDIclock source. Sorry.
Your best bet will be to find a MIDI foot controller that generates MIDI clock. If such exists. Or, more likely, some kind of MIDI merge unit such as MIDI Solutions Quadra Merge.
What you are trying to do, while possible, is fairly advanced for a guitar setup, so it will be a learning experience. Or maybe, character building.
