How can I make a fish tank taller?

So I have two 40 gallon tanks that I’m planning on merging so they become one big long tank, but the height is about 17in and I want to find a way to make the tank taller. How can I do that? Should I just buy some glass panels and use sealant to glue them on top of the other glass panel??? I was thinking of just buying another 40 gallon tank and removing the bottom glass, flip it upside down and gluing that on top 😭 I’m at a loss. Pls help!