A plate mic depends to some extent (according to design) on the surface upon which it is placed. Mounting one on a suspended plate or board should work perfectly well.

When installing them as ambience mics for induction loop systems, I try to mount them on a wall or ceiling. I tend to use the AudioTechnica ones - which are now 'mobile phone resistant'!

I also install them fairly often in churches on the main altar, and 'table bumping' isn't usually a problem.