Without the hinge it is very easy for the front glass to fall into the tank. The more oblong, the worse the probability.
In 40+ years I've broken enough glass lids that I don't use them any more. I like Lexan polycarbonate.
You can make the glass "hinge" with silicone glue. Put waxed paper on the table and tape the glass down with a nice gap to form the hinge. Not too wide or the lids won't fit!
Make sure the glass is chemically clean and make a wide, thin, tooled bead. When it dries it should flex enough to serve as a hinge.
If the glass wasn't clean, it will start peeling off quickly.