essentially that is what the idea would be. a fixed or roller bridge with the trem behind. it raises as many issues it solves but i reckon would be the way to go in order to get a trem on a multiscale. its essentially what a kahler is anyway, you have roller saddles that never move and a trem mechanism behind it. cut off the saddle part of a kahler, put on a specially made roller bridge instead... possible solution... maybe!!
problem with a floyd or floating/pivoting trem that i see comes down to the pivot point. I would guess the best place would be just in front of the high e, then you need a much longer baseplate. This means when you actually use the trem the bass side will have a lot more movement and raise the strings a lot further than the treble side. Still not sure how much of a problem that would be but i dont want to invest in it to find out.. i have other ideas - but they involve more work, probably a hell of a lot of money and still no garantees about it working well