As someone who has never used an artificial incubator I'm afraid I can't help with feedback, but how do you know that the humidity was the issue for your broodies in the past?I need @pennyJo1960 at my place! Haha saw a baby rat having a a sniff at my compost bin.
I haven't taken a chicken to the vet before, but I have spent a fair amount of time talking to the vet clinic about my chickens. I've always found them very helpful. And they dispense flock-sized amounts of wormer/coccidiostat for me, so I don't have cow or horse sized bottles sitting in my refrigerator. I live in a rural place where keeping chickens is just the way everyone used to do things and still is the way a lot of people do. The vets are very good here and I imagine they are in all small rural places here in New Zealand.
If anyone wants to follow my hybrid incubation thread you can find it here:
https://www.backyardchickens.com/threads/hybrid-incubation-feedback-please.1541686/
I didn't get any feedback on my plan yet, probably because I tend to ask complicated questions! I'll be posting updates as I go along. Should be educational at least.