Model Slipway 10 hatch coaster, Graupner Neptun, pretty sure that theres something in the Robbe range that will modify, as well as the Deans range.
Container ships offer the chance of hiding weaponry in deck containers with drop down sides (much like the WW1 and WW2 Q ships and merchant raiders with their false cargos) and the top of the container stack offers a respectable size heliport.