If you want some HD content playing at 50fps, you would more likely use MadMapper than the MiniMad.
MadMapper can output to multiple displays at the same time, but since it lacks in-between-computers synchronisation, you'll need to send your signal 200m away, using video extender solutions.
Another solution may be using small computers as nodes that receive and display the NDI signal from the MadMapper.
Anyways you'll need either long ethernet cables or a strong wifi network.
Remember using wifi will add a little latency, and the signal may degrade if the place gets crowded.