I've done the tailgate trick, it works in a pinch.
When I first brought my bike home it was in the back of my truck. I decided the best way to unload it would be a 2x6 from the truck to my car trailer, then 2x6 to the ground. I brought my trailer around with my tractor and backed the truck up to it. I rolled the bike down the board onto the trailer... I forgot to latch the hitch to the tractor and it lofted off the ball and started rollin with me and my bike on it! It didn't roll far fortunately and better I didn't hurt my bike.