@Hereforeternity and @onleana , yes, SN should theoretically work as the sole ingredient required for CTB.
There have indeed been cases of people who taken SN alone and managed to CTB. Then there are people who died of accidental SN poisoning after eating food containing enough of it.
So there is nothing in theory that suggests taking SN alone won't work as a method. All the other medicines are only to make the process easier.
Yes, vomiting out the SN is the primary concern of whatever way you decide to ingest it, either alone or with other medicines or with food/drink. Not only is it very salty, but the body recognises it as a poison immediately and would want to expel it.
So, if one can manage to drink the SN alone and somehow manage to keep it down, or manage to drink the back up glasses and keep them down after throwing up the first glass, one should be able to CTB.