Hitech,
I am not an expert at all on this, but maybe:
Disable transparency or something on the dials, and require them to be present
Place a black plate behind the dash with holes in it
I realise this may be a bunch of work so it may not be worth it, but I'd really like to have a reference angle for roping in a P38 and divebombing. Maybe it would be easiest to just change the HORZ image to something similar to:

My main issue was more just having angle reference than being able to make any HORZ I want, though I admit it's what I would prefer. Hopefully it's an easy fix and time grows on trees over there.
I realise they may have not existed back then, but my viewpoint is neither did certain gunsights we make up necessarily. It was within their technological ability and comes down to a matter of preferance.
Colmbo,
I have found a few that wrent just plane, though yes the majority Ive seen were as you describe.

