Alright so I need to cover my tank (for some reason

). I don't like glass tops and egg crates since they accumulate salt creeps. As a result I am thinking of mesh top but I am not sure how I can accomplish it in my tank since I got my whole back taken over by float switch, skimmer and filter. Maybe use several corners to lid it up? And where can I find the required things for the cheapest?
Here are some pictures for references:
And just an FTS
