Humidity question during incubation

[Buttercp]

So I have one turkey egg that is still alive and developing well. I'm on day 22 so only 3 days from "lockdown." I'm not 100% happy on the size of the air sac. It seems to be measuring more between 15-20 day then where it should be. I've had humidity between 50-55%. I've done some reading articles. Would it be safe to run the incubator dry for 1-2 days to try and get the air sac bigger or would this cause the membrane to pull away from the egg if it's done too quick? This wouldn't cause shrink wrapping would it?

Attached is a picture of the egg. I'm hoping you can make out the faint line I drew. There are two. Top one was 14 days and bottom was day 20. There are still good veins when candled.
Thank you for your input!

 

[ChickenCanoe]

Your primary humidity goal through incubation is to get the air cell appropriate or more accurately, the proper egg weight loss - in the neighborhood of 17%. Then one wants to raise humidity as hatch is imminent.
50% seems high to me. Yes, go ahead and run it dry till lockdown.
Some eggs are more porous than others so the correct humidity will vary from breed to breed and species to species.