Yes,that is one of the scenarios that I have come up with, either a drug deal, or he (Tray) spotted a bogeyman who was laying in wait for GZ. If you look back at those 46 police reports that GZ called in, you will notice that some of them didn't have a name as to who called in the report, and then some just said George, some said George Simmerman(sp) and the phone numbers are redacted. This leads me to believe that at times, someone was impersonating GZ.
My other scenario is that Tray made it onto his back porch like his dad's girlfriend said he did, and heard the attack on George, maybe he came to help George, and accidentally got shot in the scuffle. Maybe that third person had on a gray hoodie too. Maybe it was a total setup. If you ponder much, there's one particular person who fits a scenario like this.
What really bugs me is that GZ would have known those addresses...FT said GZ was over the whole neighborhood except for the small portion that he attended to. GZ would have known, and would not have had to go look for the address. An impersonator may have had to... I know this all seems way out there, but that is how it usually is in true crime stories. JMO