Thanks for the hints. I added a warning about the download size to the post.
As for the Determinante Systems installer I don’t think that it’ll bring much value here (though I haven’t tried). It can’t work around the small root partition problem. And here, we’re using the single-user installation without the daemon and builder users etc. This is ideal for this effectively single-user SailfishOS and also easy to remove. No real need for the new installer’s fancy install receipt to make sure everything can be removed cleanly again. But I’d be happy to hear what your experiences with it are on SailfishOS.