Hmmm. That is the case; 0.18 mods will install in 1.0. Although I still can't load my current save with Factorissimo enabled, I was able to start a new game.
Update: I apparently just had to give it 1-2 minutes to do some CPU-heavy work. Now it loads happily, so I'll assume it worked the whole time and I just wasn't patient enough. Thank you for your mod and your support!