Heat options

[Mimstrel]

I am preparing to transition my corn snake from the small snake rack that I keep my KSBs in, to a bioactive display vivarium.

I have only ever used UTH before, well that and the heat tape that is in the rack.

However, after a week of having the hardscape and some of the plants in place for the vivarium, I am forced to conclude that the UTH absolutely does not work for bioactive. The set up is a 20g long tank on the middle shelf of a steel bookcase. I have LED grow lights in red, blue, and white attached to underside of the next shelf up. The problem is that there's only 5" of clearance between the top of the tank lid and the bottom of the next shelf, and I'm concerned about putting a ceramic heater under there - because of the lighting, the books on the next shelf, and the heat being so close to the lid that I'm going to need to touch in order to access the viv. Does anyone have a solution for this set up? Or do I have to scrap it?