It Can Work
I've seen folks get away with this. At a track day this one rocker guy (ton up club member)was alternating his cafe'd bonneville and 60's vintage BMW on the track. To load them into his truck he put a 2x6 against his tailgate, goosed the bike and flew up the board, caught a bit of air at the top, and stopped the bike precisely in position in the back of the truck. The he repeated the trick with the second bike, dropping it into position right next to the first. The small but very impressed crowd gave him an ovation. Maybe that is routine in the dirt bike world? But it sure contrasted to the way all the other folks loaded their bikes that day. At the opposite end of the spectrum some guy pulled up with a trailer that was bigger and probably nicer than my first apartment. Out rolls a MV F4 and a 999. I love track days.