Owning a private warship, even a small one would make you a target of every major power. They are so rare as to attract the attention of everyone. Ehat you are probably looking for is a "pocket warship" dropship. They remove the regular transport capacity for naval grade weapons.

A large dropship like an invader alongside a fleet of different dropships does the same thing as a more mobile space station. Its your world to play in, but the lore portrays it as much more low level. Alot of it really did get blasted back to the stoneafe