Remember you want to be able to reach both the on/off switch AND the lock lever. You should be able to just lift the plate out with the router attached even with handles. At least with the smaller Rockler plate, I was able to pull the plate and router out with ease.
Remember to pre drill in the MDF, otherwise it will split on you. The ply will do most of the load bearing, the MDF will keep it flat. If you're a fuss budget, you can put a couple of trusses under neath, using screws through the truss and all the way into the ply. That means calculating the length of screw you'll need, and putting a stop on the bit you pre drill the truss with. You don't want the screws to get too close to the ply's surface or you'll have a little "pimple" to deal with.
The more I do, the less I accomplish.