With all due respect, by flying an approach to ditch has very little to do with visuals (in a simulator).
A night ditching has its own hazards. You won't see the water until the landing lights illuminate it. So in the simulator you don't have to rely on the visual scene to judge when to flare. In fact you may as well switch off the visuals to simulate a black night. The skill is in the instrument flying bit. To allow for altimeter error you need to be fully configured and on speed early.