Sand boa environment problems?

I recently bought a baby male sand boa and I'm having a hard time creating a stable environment temperature- and humidity-wise. I have a 10-gallon tank, with a heating pad on one side. I can't seem to get a gradient of 75 to 95; no matter what I do the entire tank stays about 85. My heat bulb makes everything way too hot, to the point where I don't even turn it on. Is there a better way to get a gradient in such a small tank? Also, the humidity is about 50%. I understand that it needs to be lower for sand boas, but the air is really humid and hot right now and the top is a screen so the humidity gets in. What can I do to fix these temp/humid levels, or am I just overthinking it?