I have the same style trays under both my enclosures with a AquaZamp and RainDome doing the misting. Here is a picture of the under side of my stand that the cages and drainage trays sit on.
You just buy the largest fitting that you want (the bigger the better, IMO) and match the bottom to a piece of 1/2 or 5/8" pvc pipe. Cut the hole in the bottom of the tray on one end or the other (I chose the left side on one and the right on the other) that's why the oval hole in the wood works so well. Just make sure that the hole that you cut is SMALLER than the inside of the fitting that you choose and use some pvc glue to stick it on underneath side of the tray. The pvc pipe fits tight enough in the fitting without any glue to hold it there. I raise the ends of both cages to allow gravity to drain the water towards the middle of the cage stands and down through the pipe into a 5 gallon bucket underneath.
It works very well for me............easy-peasy
Hopefully the picture speaks better than my typed out words do.......