What about filing as a gulfstream and it actually being a 747? I've read on these boards of air force one doing just that.
"AirForceOne" is a call sign designated for any US AirForce Aircraft having the US President aboard at that time. "MarineOne" or "ArmyOne" would be the call sign for any Marine or Army aircraft with the same occupant. Therefore, it is quite likely that more than one US AirForce Aircraft (including B747s, B757s, Gulfstreams, and others) has had, at one time or another, been designated as "AirForceOne."