Look, some of you may not know this so I'll share a bit of IRL experience.
When I was in the military I took several trips around the world. We flew in cargo planes that had seats strapped into the rows, but put in backwards for certain scenarios. Fully converted or half converted, made no difference. A cargo ship of any kind is usually built with the potential to carry human cargo, or adaptive seating is made to fit the cargo-securing mechanisms built into the cargo ship.