You got the info you asked for, fine. This 30 amps DC dimmer is sold for $122 + shipping. A Qkits 30 amps PWM is sold for 18$ + shipping. Controlling the working voltage this way would only bring down the efficiency of your generator.
Think about neutral plates. It's easy to obtain & cheap to build. 8 plates forming 7 active gaps would run on a working voltage brought to (12-14 v / 7) = 1.7 / 2 volts per plates. Looks like this : + N N N N N N -. Then adjust your amps draw with electrolyte...
Most of every things we think of and sometimes try is lost somewhere on a bench. You can always find the results of those experimentations on a forum. Amps, voltage, generator gaps. It seem we are all trying to produce HHO over unity. We cannot invent power. Making an engine more efficient, we can do... Maybe testing is the way to improove HHO world but right now, we have billions cars to equip... And a planet to save ...
Have fun !