Need suggestions for ambient temps

I'm switching to plastic to help sort out my humidity. I'll be using 2 heat mats, one under the warm end and one under the cool end - each with their own thermostat.

I've been testing it out and I can't seem to get my ambient temps up enough. I don't want to use a bulb or che cause it was the bulb in my wood viv that was killing my humidity. I don't like the idea of a space heater - a bit unsafe to leave on 24/7, especially if I'm away for a couple of days. Have I any other options?

Set you house thermostat levels up higher, and using whatever you can find to insulate the back, sides, and top. You can get some of that reflective stuff, or actual insulation. That's all I can think of right now. :D