I tried this when I was still trying to use a tank and didn't actually work. Not saying it won't work for you though. You probably should get the lamp though in case you can't keep the ambient temps up. Humidity problems can be solved with a humid hide or just by adding moss to the enclosure.
As for the thermostat everyone has been recommending this one lately, it's reliable and and cheaper than the ReptiTemp or the Zilla Temp Controller (which I use and is also very reliable but many people have had issues with it so I wouldn't recommend it).