The town will be better for humidity in my opinion. I put the glass on the side of the top that the light was on and left the side with the heating source open.

I switched to using Ceramic heaters for my Terrarium. Allows me to heat the terrarium using radiant heat (which seems to dry out the air less) and also since Ceramic heat emitters produce no light allows me to heat the enclosure throughout the night without shining a light.

I do notice that even light bulbs during the day take a toll on the humidity, but between the towel and the glass you can trap enough of it in to keep the decline slow.