I just want simple isolated microcontroler regulation that is't some insane pulsing or ugly-wave modulating but oldschool linear regulation of AC just as if it was a resistor on the knob.
Have you ever looked at ...
Why do your ceramics care about E-M radiation?
There is some various em sensitive measuring equipment around.
10m - or more, this is how far interferences can go from 1000W, 100 kHz square wave transmitter