Note that many bulkhead seats have fixed armrests, thus reducing the amount of width available for a carseat. For that reason, we've always selected seats with moveable armrests, as it was essential to fit our Peg Perego rear-facing carseat and even our Britax front-facing carseats when our kids were little(r).
And yes, depending on the seat pitch, rear-facing may affect the full recline of the seat in front. Never had that issue in United Economy Plus, though.