I got a deal on a 135G acrylic tank and am faced with the same problem. My problem is compounded because my over flow is dead center.
Has anyone tried using the stick on vinyl material used on boats and cars? It may be a simple solution if the tacky side isn't toxic to fish.

I'm purchasing a 300 gallon acrylic aquarium. The back panel is blue and I would prefer if it was black. Does anyone know of a safe way of covering this. Has anyone put pond armor on acrylic.
Yeah, I can see the side of the blue panel where it’s welded to the clear sides and bottom.Are you 100% sure it is actually a blue panel and not heat shrink wrap that can be peeled off? Just asking because on my 240g acrylic I originally thought my mine was blue until I started picking at it and found it was actually a really HD heat wrap on it and was able to peel it all off.