Ball python hisses at me in tank

The problem is that I already have him on a UTH plugged in to a thermostat kept at 90 degrees for his hot spot. The ambient temps often drop to 60 in my room as I am not allowed to turn on the heater to warmer than 60 degrees in winter time. (My mom is worried about the heating bill...:rolleyes:)
So for now in the winter I -HAVE- to use the lamps to keep ambient temps up. It won't help if they are on a heat mat breathing in freezing cold air. :(
I have already done the tin foil treatment to the top of his tank. Humidity still leaks out. He is on aspen with moss in his tank to help absorb humidity, it still doesn't work for very long, it dries out too fast. :(
I don't know when I'll be able to ditch the lamps as like I said it gets far too cold.
Also, strangely enough, when he does shed he's not aggressive at all, none of my snakes are. They don't mind me picking them up to clean at all.
He's in a 20 gallon tank and has a pretty small water bowl maybe 3 inches in diameter, about 1.5 inches tall. If I put in a large one he'll have hardly any room to move! Is it time for a bigger tank perhaps? The water bowl is also right under the lamp but it just evaporates too fast to help the humidity much. >:/

Also, no, he has no shed stuck to him. Last time he shed, he shed everything but his face part all by himself, that was about 2 months ago, and he hasn't gone blue since. The face part I gently took off by smoothing a washcloth over his face. So no stuck eyecaps as I already got them off last shed. (I still have them somewhere to prove it :P) I never take the eyecaps off with sticky tape or my hands or anything. Too risky.

If you want to promote humidity simply close the top of the cage in with foam panels or sonething equivelant leaving enough room for the heat lamp and put cypress mulch in for bedding. Mist it daily and problem solved

Thanks I will try that snake lab