no you can't fit it to the top of the ridge.
screw the two fittings on the wall about chest height.
screw bar mixer on fittings.
run two chrome pipes from fittings down through two hole in the ridge and join pipe work under bath.
pipes will only be about 15mm off wall surface.
Grand idea!! I like it alot, nice and simple...even for me
So normally when you buy a mixer shower do the hot/cold water inlets come through the fittings provided, giving it that clean finish?