Thats probably going to work best for you is getting that t-stat. Like i said, my uth is on the thermostat, and the infrared is on all the time, it keeps it steady for me. and sometimes it gets really cold in my room.
What kinda cover do you have on the cage? The one i have is tinfoil and duct tape. It makes a HUGE difference in the heat and humidity. Like 15 degrees difference.