I'd like to have something ugly down there, to highlight the fact that this is a change of plans, a last minute addition, and to create contrast with the otherwise smooth lines of the ship. I'm weird like that.
So, perhaps a protruding quantum torpedo turret á la E-E, a clumsy and unwieldy weapon that might end up being more trouble than worth.
Or another type of deployable craft, but this time an uncrewed model - a Transformer-like, clickety-clack robotic device that would unfold after deployment into... Well, perhaps a floating observatory to be left behind at an interesting spot? Or a complex planetary survey base that soft-lands on a moon or an asteroid.