Somethings

[Suicide Junkie]

Suggestion: Mine-Class cloaking built into a vehicle, with room for only: 1) A micromounted Star/planet killer, and 2) A micromounted one-mp emergency propulsion pod.

The mounts will allow you to restrict the components to that particular hull only, and you can add "one-per-vehicle" restrictions as well.

If it works, use a base hull. The emergency propulsion pod should allow you to use your device while not allowing movement.
Otherwise, just use a ship hull, and accept that it can be towed around by a repair ship.