Looks like the 5th man was essentially the same concept as the E-Bow/Sustainiac/Fernandez Sustainer only instead of the drivers firing up from under the strings they went transverse across the strings -- interesting solution.
You're absolutely right about ahead of where technology was at; the E-Bow came around in '76 but had the advantage of several years of innovation in electronics to work with.
The Project V fuzz is best known for "Here Come the Warm Jets" by Brian Eno -- in fact a UK company, Ghost Effects, did a reproduction of it a few years ago and called it the "Warm Jet".
EDIT Found a cool page with more WEM stuff on it
here
BTW if you ever come across an Espana brand guitar/bass it's a WEM that was rebranded for export to the US.