You can make the holes bigger and then put chicken wire pig wire or hardware cloth over them. Then lay the lights on top.@leigti
Perfect! Two of those would be even more surface area. Maybe this is a dumb question, but if you only cut the holes big enough for the lights, would she get enough fresh air? I've seen herpers with tote tanks cut out the center of the lid and replace with mesh, but then in this case it would hold less humidity. I guess from when I had a chameleon I just stress about poor air flow and the respiratory issues that it can cause. Maybe box turtles aren't as sensitive though?
You can use one of these or maybe a couple in a couple different spots at turtle level in your enclosure to keep track of the humidity and the temperature. It even tells you what the highest and lowest humidity and temperature have been for the last 24 hours or so. Adding water to the substrate, especially under the heat source will help raise the humidity also. And live plants really really help. I put some in pots and some I just planted into the substrate. This is an example of my box turtle enclosure, it had an open top so I jerryrigged a cover with a clear shower curtain. Make your life easier and just cover yours with the lid there are rocks and little logs and a deep pile of moss. I would throw in crickets and worms and she loved it.