ok, here's my build
3 machine guns at the bottom, spread out a little (to catch what you could miss)
2 lightning rods at the topmost left and right corners (for max range (strangely they seem to understand what side they're on and act accordingly))
3 missile launchers packed onto the ship (I'm not really sure if there's really a strategic placement for them)
all of which are level 5 of course ;D