Welcome to geekhack.
For clickies you should use a metal plate like aluminium (which is my personal recommendation) at least when it to customs. The clicks feel far more solid which is what I feel most people want with clickies + sound more crispy.
For mounting, most mounting styles should be fine for a keyboard, but the best board I ever tried with clickies was top mount which would make the switches far more solid feeling compared to o ring mount so maybe that could be what you are looking for (if you want to know the board, it was a duck lightsaver v3 with box jades, but you would have to go to the aftermarket for that one, and any other duck boards)
also the drop alt is a tray mount as the screws are fastened into mounting points from what I'm aware.
I have heard the mode boards are alright, and would personally not get anything from kbdfans, I've had issues with quality control (even if it was a minor thing) along with hearing many other negative things that I have heard so I can't really tell you anything about them.
Hope this helps you