it's also how cruise ships are built. they slide in the suite into an opening. Also maeans upgrading them just means taking out the suite and putting in a new

it's also how cruise ships are built. they slide in the suite into an opening. Also maeans upgrading them just means taking out the suite and putting in a new or already refurbished one (i.e. if its a standard cuboid, get the X needed to "upgrade" cruise ship A ready, take out all X of cruise ship A's modules, replace them with the refurbished/new ones, and then refurbish the ones you took out of ship A for ship B....)