The problem with a French 75, which is a mighty fine cocktail, is that you'd have to drink an unhealthy number of them to finish a bottle of champagne before it went flat.
This has nothing to do with TFA and the math therein other than it's a cocktail on the list.
just invite more friends over and make it batch style in a punch bowl. still will be an unhealthy amount unless you have a lot of friends, but you will have a good time.
no idea on the accuracy or veracity of the history of the name (as is pretty common for cocktails) but i always loved the explanation that the drink is called the french 75 because it "kicks like a french 75" meaning the 75mm artillery gun used in ww1.
I do know that gun exists and you can see it on display at the ww1 museum in kansas city. Having never seen one fired i can only assume how much it kicks but it is pretty large, and working backwards from the efficacy of the drink i suspect it packs a whallop. still a great name, great drink.