No need for the 747, a G-5 can carry the number of people on the trip.
My comment was in relation to fuel. A G-5 has the fuel capacity to make the trip but I question if it can carry a full fuel load with that number of passengers, just a question, I don't know and haven't gone to their web site to check stats.
Something is strange here. One of the pool reporters wrote a detailed account, which can be found here on FreeRepublic (search "pool"). He states that they disembarked one Air Force one at Andrews and got on the second 747 used as AF1, and says that he saw the Prez get on as well. However, upon takeoff in Texas and landing at Andrews, the compartment door was closed so that the press could not see the Prez's arrival and departure.
He doesn't state whether the door was also closed when the flight was about to leave Andrews for Baghdad, but if it was closed, perhaps the Prez boarded in view of the press, and then got back off and boarded a Gulfstream? Otherwise we'd have to believe the entire pool of reporters agreed to not report the fact that they switched planes somewhere along the journey.
Also in the account, the pool reporter describes a question of the Communications Director regarding what designator the plane was flying under (Air Force 1 or something else). The Comm. Dir. responded to the effect that this plane was not flying as AF1. Perhaps the conspiracy theorist in me is reading to much into his use of this...or am I missing something else?