I was thinking about your temperature fluctuation issue & wondering how long it takes to recover. The eggs can handle it if it recovers in a few hours. My incubators are the plastic dome type & I have to remove the whole dome lid, which exposes the eggs to a big temp & humidity drop, which recovers in a few hours. I used to worry like crazy & try to readjust, which caused temp spikes, which caused eggs losses. Now I just come check on it in a few hours after putting the lid back on.
People who have many power outs due to weather, etc. have posted using small jars with water & lids, or even smooth rocks to hold the temps longer. Others have said they use these to help recover temps when they remove the lids for turning, etc. Maybe these could be easier solutions to recovering the temps. Good luck with that.