Now I'm confused... Are you saying that controllers can't solo level 54 AVs without damage mitigation? I'd say that's pretty much a given.
I chose my illusion/storm over my illusion/dark because of the comment you made about to-hit debuffs being helpful when you aren't at capped defense, the concept is the same though... PA doing the tanking and some damage while I whittle away with tar patch, blind, spectral wounds, with howling Twilight there to do a good chunk of -Regen.
If, however that is still out of the scope of what you're looking for, I suspect a dark/energy perma-dom would be a good choice. I can't crunch the numbers right now, but I suspect with power boost and clarion radial you could get the ~10 stacked confuses needed to confuse through PToD, then your pets could (slowly) whittle away at the AV while you basically just keep confusing it and throwing in an attack randomly when you aren't casting confuse/hasten/PB/clarion/domination