The cover is an excelent idea!!

But, I read you asked about keeping the water level low-

You can do this, you just need to maintain it to keep parameter swings and such from happening. I am doing this exact same thing right now.

I can keep my tank almost an inch low without getting to much noise out of the tank. If my tank gets loud- it reminds me to top off- right now. Its almost like an alarm clock to top off, and keeps the swings in check!!

I have a few jumpers in my tank- and no lid yet....one day I will do jims mesh top. Have you seen the post about light penetration and the mesh top vs. other tops??? Great thread to check out.