I've no doubt it can be made to work, but preventing it from interfering with everything else in the area and on that mains circuit would be a major problem. What do you see as the advantage over a phase angle SSR?
Have you tried using a zero-crossing SSR and switching it on/off potentially on every cycle of the mains? For example, when you want 50% power, instead of 0.5 sec on then 0.5 sec off (which might give a noticeable flicker), turn it on for 1 cycle, then off for 1 cycle, then on for 1 cycle etc.