using some scrap I worked out the cut pattern for the under side of the nose. I then fit up the housing in the whole. The nose was set level up so that I could also level the housings.
I slotted the top of the PVC so that the leveling adjustment screw on the fixture could be used. Once I could slide the unit into place I made the back of the housing out of some lexan cutting out the back to clearance for the bulb and enable the plastic clips to hold the unit in place.
After gluing the back on the housing I fused the housing to the nose.
I mocked up a chin spoiler out of sheetmetal to look at the proportions. The lens on my camera is kind of a fish eye or wide angle so although the chin spoiler is big it looks a lot bigger in this picture than is really looks in person. Be that as it may I have to tweek on the spoiler a bit yet to get it where I want it.