I guess I have mine setup a little different. My output is in the back right corner of the tank now, pumping water towards the front left corner. The intake is about two inches off the substrate in the back left corner.
Aiming it towards the front pane just creates too much turbulence, imo
. My 75g is a little deeper front to back than a 55g, I can only imagine how much worse it is.
I think the 40x's provide plenty of room for media as is. I'm running sponges on bottom and side. Bio rings in next two and polyfill in the top.