Update: To further isolate the issues, I pulled the monitor entirely out of the cab, and the chassis off the monitor frame. While I'm still not getting sync, it's closer than it was, but more importantly, it's NOT making those worrisome noises, and NOT making anything in the PS area smoke (to be clear, smoke was never coming from the switching PS, but possibly just from AC wiring, or the iso trans, thereabout).
This is good news! But still, no sync, and what's going on when the chassis is attached to the frame, and the frame is inserted into the cab? The only thing the frame touches once in the cab is a metal bracket on the left side -- the only thing touching this metal bracket is an earth ground line I've got running through the cab, down to each PS part, and into the earth ground input on the switching PS. All of this was carefully done according to Bob's article. Could it be that earth ground causing issues?
Furthermore, I noticed that in this external setup, when the video pins (RGB gnd sync) are NOT attached to the chassis, I happened to take a reading off the monitor frame and get 109v AC. Uh what? Isn't that the job of the iso trans? Once even just the RGB and sync are attached, that voltage off the frame goes to almost zero.
1) no video pins connected, getting 109v AC off of monitor frame
2) all video pins connected (RGB, gnd, sync), getting .05v AC off of monitor frame
3) some video pins connected (RGB, sync, NO GND), getting 1.8v AC off of monitor frame