I'd be glad to chime in. First, you're right. Just leave snaps undone if you want more ventilation. I'd rather have more than needed than too few since you can choose to use them or not. (It takes a lot of snaps to even begin to register grams on my very detailed scale).
These are specialty Industrial snaps. It could be a bit pricey to use the same ones I do for a DIY'er, as the apparatus required to affix them costs in the three digits - it's a very specific type of snap and won't work with standard snap press die sets.
There are companies that sell sew-on snaps that might be a more cost effective solution for the DIY'er.