F150 with 6 1/2' bed, but I load the bike with a rampage. takes about 15 min. and I'm on the road.

before I get flamed, I use it in the winter to get south of where ever the snow is!!!

 

Why not put a 4 X 8 sheet of 3/4 or 1" plywood in first, that would be more than enough support for the back of the bike without worring about the tailgate.

 

I won't trust the cables on the tailgate at all. Been through a few on my 2000 Chevy. I've never had more than a few hundred pounds on the tailgate. They rust, get pinched, the ends pull off.
Even on trucks with the steel plate supports the tailgate could get bent.
I remove the tailgate if I'm loading or unloading anything that I can't lift with one arm.