Reviving this as I've seen some inspiration that may allow for a retry of this design:
My suspicion (which was never verified, as I moved right around the time I posted last) was that the issue related to the LC output configuration not having anywhere to drop ripple voltage. Which makes sense, as a "normal" linear supply filter (no inline resistor before the Cap) like I was using creates an output equivalent to the Vpeak of the input rectified waveform, not the RMS or midpoint. Freshman level stuff, and I flunked it
. What is needed is a decoupling capacitor (to convert the PWM signal to an analog DC value) and then an RC stage (aka the linked capacitance multiplier, ideally using the same model MOSFET as the first stage) to filter out the ripple, no massive inductor needed. This will probably throw a wrench in the works for the PCB layout (double the # of mosfets with heatsinks, which I may try to run without), but that's besides the point since the old design was junk and not working.
I've been bogged down with work and homeowner chores, and may not get to this any time soon... But with any luck I'll have some time over the next few weeks to breadboard a circuit and give it a test spin.
Am I possibly on the right track?