EXIT ONLY tatoos on their butts?
This type of behavior, no matter how risky (risk is part of the attraction, seemingly) is going to continue despite the attempts from outside to intervene. Even attempts from within the subculture have not been effective in putting a stop to the spread of disease. AIDS seems to be the only disease we discuss, but there are a multitude of others that are spread quickly by the same means.
The only real chance we have of beating this scourge is finding a cure. Certainly, and end to gay sex would be a start, but it ain't gonna happen. What is needed, is an innoculation like we have for so many other deadly diseases that used to take lives - we never give them a thought these days, except as the name of a shot on our medical records.
We can't hope to control human behavior. When has that ever worked well?
The CURE for AIDS was available and told to people as far back as AIDS started becoming generally known.
The cure is: Keep it in your pants.