Alrighty, so booked an Intercité de Nuit from Paris to Antibes and back. Relatively painless once the connection is actually listed. Nice. Also: 330€ for two adults and two kids in a private couchette 2nd class.
Given that an extra night in Paris easily costs 150€ that's actually pretty cheap.
Also: the ICE Darmstadt Paris and back is 360€.

Let's see how it goes down. #CrossborderRail #train #europe #nighttrain #InterciteDeNuit