Up front: Calamares (Kubuntu installer) didn't cut it. So I went the well-trodden path of manual installation combined with later package selection that would mimick what Calamares would have picked.
These instructions make assumptions. The main assumption is, that you dear reader, are not a numpty. Therefore use your own judgment and adjust arguments (especially device paths) to your own needs. Don't blame me for doing stupid things on your end. Got enough stupid decisions of my own to deal with ...