When you build a screen for a tank that will have heat lights sitting on top (especially ones that need to produce as much heat as you need for a beardie), you
MUST use metal screening. Fiberglass screen is covered in plastic and it WILL melt, as well as release fumes. If your lights are going to be suspended at least two inches above the screen (at the very least), you can use "door screen" (fiberglass screen).
Lowcountry, I hope you still have the screens intact. If so, youcan buy some small hinges and hinge them in the middle so you can have an opening screen. You will be so much happier to be able to open it that way without having to remove it.
(lmao, I wrote that BEFORE I finished reading your post... I think I'll leave it to show how great minds think alike.

)
If anyone wants pics of the screen lid i made for my beardie tank, I can take one when my hubby gets back with the camera.