Personally I'd get rid of the humidifier, being tied to filling it up every 8 hours is a nightmare. I tried a bigger one but had to fill it every day, I ditched it in after a couple weeks. Now I just spray the substrate every 3 days and let it get a bit dry between sprayings. The only way I'd go back to a humidifier is if I had a reverse osmosis unit hooked up to an automatic water supply feeding the humidifier so I'd never have to mess with it. I do keep the substrate damp if they go blue until after the shed. I don't worry so much about having exact humidity, it's really only important to bump it up high during a shed, otherwise it's find jumping around.
I'd also get rid of the aspen, it's difficult to keep the humidity up. I'd switch to a coconut husk fiber like Reptichip. It absorbs tons of water and keeps the humidity up and keeps the snake dry because it doesn't get soaked to the point where you have a puddle.
If you can't control the heat I'd pull all heat sources, better to be cold than burning hot. You can always crank up the room temp to the mid to upper 70s with a space heater until you can get a good thermostat. I have a whole box full of dimmers and $25-$100 thermostats that I don't use anymore, I finally upgraded to a couple Herpstat 4s. If you get one with the 'pulse' heating it will maintain temps better. I tried the cheap ones on Amazon for about $25, the temps vary up and down about 10 degrees, they are too variable for my taste. And I don't trust dimmers in the long run. The pulse thermostats will only vary a few degrees. I'm of the mindset of thinking that good equipment has good resell value if you ever want to get rid of it. And if you buy junk you'll end up with a pile of junk that you'll never be able to sell and will eventually upgrade later so it becomes obsolete. Better to get some good equipment up front if you can afford it. I was actually bidding on a Herpstat 4 on ebay, my max bid was $300. It sold for about $20 less than a brand new one, so I ended up just buying new. If I ever seriously got into breeding and had my own building with heated and humidified rooms I could sell all my Herpstats and get most of my money back.