I forgot: block the port. Phase inverter designs are really sensitive to the driver T/S params, sealed box designs are much less sensitive. No, Focal automotive speakers T/S params are published. Nothing special or unusual. Tried, tested, works.
That's one thing you can't really do with powered monitors--blocking the port! Can cause the amps to overheat lol.
Other downside I see is idle noise can be an issue in low ambient noise levels in the nearfield. This gets even worse with analog input sources. With passive speakers, a receiver will usually have a set of multichannel inputs specifically for analog use that have the lowest noise levels that you can use, and actually one reason I love low sensitivity hifi speakers--low noise level with analog sources. One thing you will notice immediately between passive speakers--hook up some high efficiency 98db Klipsch speakers, and the passive noise floor goes up compared to hooking them up to some extremely low efficiency 82db Salk or Usher monitors. This tends to be great for quality of life nearfield that you just cant achieve with powered monitors.