I also was able to get my bike through the rear door, but it was a 600cc sport bike. Like jimmy said ya might have to walk the handle bars through one at a time. The Hawg Wagon
seems to fit a larger bike through it's rear door.
I've hauled a 2nd bike on my rear deck once, it works but I think a trailer is a lot more user friendly than a rear deck. My rear deck
is about 3.5 feet off the ground, unless you can find a hill to back up to it's nearly impossible to load and unload a bike. I park next a hill at my house and mainly use my rear deck for my quad (the ramps for loading are nearly level) when I get to where I'm unloading it I just pull it off the deck with no ramps and let it drop to the ground.