I followed some of those links and had a good laugh. The article on Wikipedia made it sound like Dog Man Tony and Dan Boone are very mysterious characters! I got a kick out of that.
The FTRA exists, and several of the guys I know now broke in riding with the FTRA, back in the day. I've drank beer and whiskey with Dog Man and the late Eight Ball and met several others who would probably not appreciate me mentioning their names on here. They are plenty tough, but this "killers on the rails" stuff is nonsense.
Robert "Sidetrack" Silviera was arrested and convicted of multiple murders of old timers (for their SS checks and I.D.) and a few "yuppie hobos" that he apparently wanted to rob. Dog Man was arrested during this investigation, but eventually released for lack of evidence. The cops were just trying to make a case against anybody and everybody they could catch.
If you mind your own business and avoid confrontation with these guys, they generally won't bother you. Drinking and doping with strangers is always a bad idea, but it's an even worse idea with the FTRA. Would you get drunk with the Hell's Angels or the Bandidos and then get into an argument? Well, then don't do it with the FTRA.
Avoid trouble. Do not drink with strangers. Never get involved with a girl or woman travelling with other tramps. Other than that, the FTRA is no more dangerous than the average 1%er motorcycle club.