You might have some luck if the bikes were lying down on top of each other rather than stood up. Not sure if this would be acceptable though.
I prefer my bike stood up and straight so they can be secured, and this requires taking the front wheel off. My 29er may also need the bars steered to 180° to additionally reduce the length. It fits about the same sideways too.
Maybe someone here would give you a go, our just go to a trail centre and ask.
Very happy with mine (03 plate), I even have a fold away conversion for sleeping in it.