Hello and welcome to FF! Your room temps are below those recommended for FBTs. If you describe your hood and maximum wattage capability maybe we can recommend something that will work. A heat pad on the side glass controlled by an automatic thermostat or manual rheostat could work; but they are not very efficient and loss heat to air around them. Also, water splashing on a hot glass could crack it.

If you get a screen top, then can lay a dimmer type dome made by Fluker's on it. A small 60 watt ceramic heat emitter should be enough to help warm them up a bit and you can use the dimmer to dial temperature in. Recommend cover the rest of the top screen with aluminum foil to prevent heat escaping to ambient cold air. Myself cover the whole screen first and tape the aluminum foil to the screen top edges. Then using a Sharpie, mark around the perimeter of the dome or light fixture and use scissors to cut the hole open. Good luck !