The concealment and stability problems of a containerized arsenal ship

Could an ordinary container ship become an arsenal ship by carrying launchers inside containers?

Yes, as a rapid conversion, but container dimensions, targeting, stability, and launch-exhaust arrangements would constrain the design.

Containerized missile launchers offer a way to convert a merchant ship rapidly into an arsenal ship. An opponent would have difficulty distinguishing an armed container ship from other vessels of the same type. Container dimensions would constrain the weapons and equipment that could be fitted. Targeting arrangements, stability, and the route for launch exhaust would still need to be worked out.