Cargo ships are currently using diesel engines that weight up to 2,300 tons and carry more than 15,000 tons of fuel. The ITER core currently weighs about 5100

Cargo ships are currently using diesel engines that weight up to 2,300 tons and carry more than 15,000 tons of fuel. The ITER core currently weighs about 5100 tons. I'd expect refined fusion systems to be able to come down in weight. Even if all the supporting infrastructure weighed more than the combination of bunker oil and diesel engine, it'd have to be a lot more to negate the advantages. As far as too complex, that really depends on the commercialization potential of fusion and how complex final designs are.