I use heavy duty aluminum foil on the top of my screen, and have a hole cut for the CHE bulb and dome to sit on top. Three sides of the tank have Reflectix (the silvery bubble wrap type stuff) taped to them for insulation.

A UTH will do nothing for ambient temps. You are going to need a heat source on top as well, with room temps that low. I would get the same size CHE for both sides, and lamp dimmers for them so you can adjust them. As I said, mine sits on the screen, but I have a stand to hook it on for when I need to open the tank.

**You do have a thermostat for the UTH, right??

Make sure you have a digital thermometer/hygrometer on each side. Walmart has a good one in the Acurite line. This way you know for sure what the temps on each side are, though there are many here that have a temp gun.