I Hope you can understand this scenario to help answer my question...

Say you have a ship that has a 360° attack (K-Wing for example) and they want to shoot at a ship that is flying perfectly parallel to them (sides are of equal distance, and the front/back are also in line) and there is an asteroid that obscures over 50% (but not more than 80%) of the firing passage....

Rules are Closest Point to Closest Point for range etc... but if the closest point is equal, is there a specific origin and destination of the attack that would deem it defended behind an asteroid or exposed? like Peg to Peg?

The attacker chooses where that point will be.

It doesn't matter if the ships are on a parallel course or facing each other. If the closest to closest distance is the same from either corner of the base, then the attacker chooses the line of sight for the attack and if that line bypasses an asteroid, then that attack is not obstructed.

Awesome... thanks!

Perfectly parallel ships can have distance measures at any point along their sides that is perpendicular to the other ship.

Now corner corner may NOT be the shortest distance between the two ships even if they have parallel sides. It is if they create a rectangle but not if there is some angle to it creating a non-right parallelogram. The only way to have multiple "closest points" in common is if the measurement is taken perpendicular (at a right angle) to the ship's base.