If you put that pvc grate a little more forward you could wrap a half circle of mat from back corner to back corner around the pump to get two layers of mat in there. I'd probably try a brush laying down under your screen, or forgo the screen altogether and put a full row of brushes across in front of your mat...
I'm always trying to figure out how to get more filtration stuffed in my skimmer. If your bottom drain does draw, you'll get more glop in there and it will load up your mat in no time. Brushes are easier to wash out.
Looks like you've made a nice solid improvement there.