I've seen pictures of half empty jars with lots of airspace on top. Just a random thought about getting the oxygen out of to keep any nasties from growing before the fermentation kicks in.
Ah, I get where you're coming from. I suppose it would work. Usually the salt keeps the nasties in check at the start. I often add a leaf of cabbage on top of the peppers to get the fermenting started fast and get the gas cranking. The cabbage leaf can be eaten or discarded at processing time.
No one in our area has dry ice, ever, there are a few stores 40 to 50 miles that carry dry ice in the summer.
If you try it, post pics and tell us about it. I'd love to know if it works.