Yes, if they are denting much this early you could put the water pan in as they are apparently dehydrating. Of course, if they are infertile the water pan will not help.
Maybe my vermiculite was too wet last year when mine where swelling too big before I pulled the pan out of my incubator. I read about an egg (another species) actually splitting and I don't think a high-pressure environment is good for them but I really don't know for sure. VPI recommends that they be a little collapsed by hatching time for fear of them drowning. I know I've seen corn eggs so full they squirt when piped hatch fine but my preference is to let them dent a little slowly along the way, mostly near the end.
JY,
What is your thinking on not candling? Do you feel that it is a risk to the eggs? I guess I could see any movement as a risk and possible temp changes. I had some good-looking eggs (i.e. not slugs) last year that I believe where infertile (I opened one that didn’t start looking bad until halfway through incubation and found no embryo in it). If I had figured this out right at the start I would have saved a lot of time and headache trying to save the unsaveable.
I also don't recommend misting them or towels over the egg.
Perhaps your papertowel substrate doesn't hold enough moisture and hence the need for a water pan. With my damp vermiculite and fairly tight incubator I don't need the water pan. Then there is the no-substrate 100% humidity method so obviously there are many ways that work.