I put my turkey eggs on lock down last night and did all of the necessary things for lockdown. I filled both trays up with water and kept my sponges in the tray. I placed paper towels under the eggs so the poults are not slipping and sliding in there once they are hatched. Well, I checked the humidity about 2 hours later and it was down to 35.

That was a first. So, I had to find a little cup and added more water to increase the humidity. I hope that helps it. Sunday is the scheduled day to hatch, so I hope that all goes well. Now that I'm thinking about it, I will have to move the cup to the bottom where the trays are so that the babies don't fall in and drown.
Good of you to see the hazard!! How about a wet sponge? What is your goal humidity?
I use very small baby food jars and poke a sponge in to the water with the top of the sponge out of the water. The more that is out, the more moisture going into the air. THe poults can't fall into my set up.
I have wet sponges in there and the humidity was still at 35. I'm shooting for a minimum of 40 for the humidity. I will have to come up with something else before Sunday.
I don't know how much space you hae to work with so I'll toss out every ide I can think of, then you can see if one might work:
I put in 4 baby food jars with a sponge poking out and filled with warm water.1-4 jars
square tupperware, sandwiich size, with sponge and water
wet paper towels, need rewetting often, and can't block vents
Increase the humidity in the room that the incubator is in. Some people put a source of moisture under or near the in-vents to draw i moist air; carefull not to block air vents.
I like using the sponges because I can microwave them to disinfect; I can also get the humidity over 80% on my LG.
Good luck!! LEt us know what works.