Some put the deli cup inside a piece of cut pvc or a higher price pvc pipe coupler. It looks like this http://royalconstrictordesigns.com/u...23e552c2c7.JPG
They do this so the easily flipped deli cup is more stable and not flipped as easily. They use the deli cups because they are cheap and easy to replace instead of cleaning a ton of bowls.
With my collection I use mostly ceramic dog bowls. They are easy to clean and hard to flip, I have never had one flipped.
To boost your humidity add moss to your hides. I take a big clump, soak it, and stick it in the hide. During a shed I keep it moist by misting it when needed. During a non shed time I allow it to dry out before soaking or spraying it again. This will create higher humidity in your hides and since your snake stays in the hide most of the time it will benefit from it greatly.