I had the idea somewhat early on, but discarded it again, so when it became reality I was going through the situations from the book that did not make sense in the light of this. Much similar to Fight Club, actually, where I wanted to yell "are you guys fucking serious?" and a few viewings later loved the film of course.
So I wonder how many clues are there throughout the book. If there are none, I'd feel cheated. I hardly ever get around to re-read a book, so I may not know for a while, but I really hope there were fair clues. People reacting differently to both Gonzo and our narrator at the same time would not make sense, for example. I like to think Harkaway was smart enough to avoid such traps and I merely didn't notice.