No RSI needed. You have drug assisted crash airway? (Versed maybe)? And with a GCS of 3, you probably don't even need that.
I'm sure as heck not criticizing you. Jut remember that anyone that depressed, with that much of a toxic substance on board is at an EXTREME risk of loosing their airway in a flash. I know, I have had someone with a seemingly patent airway, and 30 seconds later, I am trying to move at light speed to get it back.
He vomits without an airway in place, and suddenly those are the longest three minutes of your life, plenty long enough for him to arrest.
Just my $0.02. But then again, I am pretty darn aggressive when it comes to airway management. More so than most I would think.