If flying in atmosphere, mines would be useless due to planitary gravity, so missiles would be the more logical choice. But this is a fast interceptor, it makes lightning slicing attacks straight through nme formations, so any battle would be preferably short and intense. Rear missile banks or mine hatches would be kinda useless imho. Unless it is a less manouverable 'Broadsword' (still love that Wing Commander design ) class bomber, flying like slug on wings, trying to make it to the main objective.
But if you do want to add rear defensive/offensive weaponry, may I suggest slits somewhere in the fuselage -maybe by adding 'bumps' onto it- to carry micro-missiles with multiple warheads? Somewhat the same idea as passive chaff, but with 99% chance to hit nme missiles by actively seeking threats and damage/destroy nme fighters that are too close on the tail of this interceptor.
Just a quick brainstorm.
I forgot: do the wings have enough lift when flying within atmosphere? Adding panels for vector-thrusting on the exhaust of the engines might help improve the manouverability without having to use the bottom manouvering thrusters extensively just to keep it in the air and create more lift? I'm not an expert in flying though, dunno if it works.