There have probably been many survivors. But again, by the nature of this "almost perfect" crime, the victims have antegrade amnesia. Antegrade amnesia is probably caused by the "mickey" that they have been slipped when they are drinking. I think the
"mickeys" are probably GHB, PCP, or LSD. Here are links to 2 recent probable failed SFK attempts.
Footprints At The River's Edge: Fargo teen hospitalized after being found in subzero temps
Missing college student found - Buffalo.YNN.com
Note that Jacob Eichelberger was found without his coat and shoes...in Fargo...in January. PCP and LSD have the side effect of making people feel unbearably warm, to the point of stripping off their clothes. As far as I am aware, GHB does not have quite the same effect on body temperature. But these SFK people have been doing this a lot, have had lots of practice, and probably share their tips and tricks with each other. My hunch is that they actually use a blend of psychotropic meds...maybe some GHB spiked with LSD or PCP. Since their victims are usually males between 150 and 180 pounds, the dose is pretty much always the same.
If you watch the video of Josh Szostak coming out of the bar, you note that he does the same thing. He's struggling to do everything he can to take his coat and shirt off, in December...in Albany, NY!
Josh Szostak - The Video | Smiley Face Killers