1) Is any portion of the enemy Hull Zone within my Arc of Fire? ANY Portion?
If Yes:
2) Can a line be traced from the Yellow Dot of my Firing Zone to the Yellow Dot of his firing Zone without crossing any other part of the DEFENDERS Hull Zones?
If Yes:
3) Measure Range using the Closest Point of the Enemy Hull Zone THAT IS IN MY ARC OF FIRE.
...
Boom. All Measurements Done.
All you need to account for now, is if the Yellow-to-Yellow goes over an Obstacle, -1 Die.
In application, its really not that complicated - it can be 'annoying' when that really wierd corner-case comes up, but 95% of the time, this stuff is straightforward and simple - it doesn't need complex theory...