Making a plexiglass top with a few holes drilled in can really help keep the heat and humidity in. Lowes has plexiglass they will cut to whatever size. I made one with a hinge in the middle and one side somewhat fixed. It is easy to open. I also made a little latch so it can be locked. That might help the temps.

I keep my BP's cage in the basement where it gets cool. I bought a ceramic heat emiter on a dimmer that I use for supplemental heat in the cage. I mounted it on my plexiglass lid and have a gaurd around it to prevent my BP from being able to touch it.

Good luck.