What about some decent LEDs in the normal housings? Not the rubbish ones on ebay, but proper ones as per Youtube videos.
Unfortunately, projector lamp washers are part of the MOT check, as is visual inspection of the level sensors. I guess they also check for the xenon startup test where the beams move around for a couple of seconds. Not sure if aftermarket projectors do that.
If mine didn't already have xenons, I would not bother retro fitting them. Not worth it. They're not that bright for one thing, they wobble over bumps (worse with uprated suspension) and the lamp housings are physically bigger than the regular ones, which causes an annoying bumper gap.