That's similar to how I have it, though I have holes drilled into it. Aside from reducing the splashing, a few things will happen:
The plexiglass will eventually warp and curve in. When this happens, it will be slightly more noisy.
Mildew slowly builds on the tank behind this area... at least it did for me. Not a big deal if you clean your tank on a regular basis.
This really limits water circulation to the area around the filter. I have an XP3 at the opposite end of the tank.




