Converting to a single FMIC would be a nightmare your best bet would be a FMIC that is really two IC cores welded together. Still its going to pretty hard to shoehorn in there and a plumbing nightmare. I know guy in the UK that had Miltek look at it and they said it couldnt be done at least with the stock bumper.

And thats not an RS4 bumper its either a Lltek or a SGI.