[titannet]

A "normal" ocean-going Ro Ro ship would be over 200m long and quite a bit higher. Typically only the lowest deck can carry trucks and heavy loads and the upper decks carry cars. Their solution of only having the heavy load deck is sensible since they need a low center of gravity to counteract the sails and any added deck height hurts the sailing characteristics. With all that said, there is not much to scale it up. They could make it a bit longer but probably mostly easily: risk in bad weather, structural integrity demands from the added sails and all that may quickly add up.