I find that soaking a bath towel, which holds a lot of water, and laying it over the screen top helps a lot. Squeeze it only until water doesn't drip, but is still very wet. For you, it might last a day.

You can also use substrate like coco husk or coco fiber, which holds humidity better, if you're not already.

I also make humid hides by just sticking the inside of the hide with paper towels and spraying them wet again whenever needed.