I am closely examining the issue of humidity as well...I don't see why I couldn't put my microwave to use (no...not on the eggs!
)
Heat up water in a pyrex or otherwise microwave- safe container, and then add the still-steaming contents to whatever reservoir is employed in our respective incubation systems. If nothing else, then utilize a spray mister bottle to lightly mist-coat the inner walls of the incubator chamber, and if advisable, even the li'l hatch-berries themselves - with a sheen of water at +/-102 degrees. This should counterbalance any (minor and temporary) loss of heat owing to the opening of the incub. chamber.
Sure, it's a balancing act, but isn't this whole process?
My first hatch, and things continue apace - I am starting to get more excited! I did a last candling and "sniff test" run through my remaining 14 Ameraucanas last night late. No stinky eggs here! Here in another 45 min to an hour, I'll give them their last turning, prelockdown.
From then on, it's on them and "nature" (and "nature's G_d", as our Founders once wrote).
Lightfoote
"Thy word, O Lord, is a lamp unto my feet, and a light unto my path."