If you're sure your hygrometer is accurate, then I'd do the following:
1.) See if you can get rid of the red light.
If you can't then:
2.) Move the water bowl closer to the UTH.
3.) Exchange the towels for tin foil and cover most of the top except for where the lamp is... I would just stretch the tinfoil across the entire screen, then carve out a circle an inch bigger than the lamp.
What water bowl are you using? If it's that rock-like thing, you might want to exchange it for the lighter plastic one.