When we travel with our Honda 200, we transport in the van with no problem as far as gas smell goes. The gas cap has an open/close setting. At most we sometimes get a faint smell from the unit, but it is not gas.
The trick is to make sure you pack the generator really well so it does not move around during travel. When we get to destination, we take the unit out of the van.
Is this the SAFEST method? Probably not, but use your own judgement and be careful.
Sometimes I wish I were living in the stone age. Then I would know I'm the smartest person in the world.