The generally accepted enclosure size is 2/3 the snakes body by 1/3. A 20 gallon long is the biggest I've seen recommended. The don't need room. The spend 90% of their lives in a tiny hole in a termite mound. Room is usually cited as a cause of stress. Under tank heat and a thermostat will give you much better results, as well as a smaller enclosure. I recommend Flexwatt, because it's infinitely cheaper than stick-on UTH pads.
If it's eating, shedding, and not roaming during the daytime, you're probably ok, but UTH will be much easier on the humidity, and with a thermostat, just as safe. Possibly safer. Those lamps get HOT. I burned a hole in my carpet being absentminded...
I've read that soaking may be because of low humidity.