I noticed you pulled the front suspension in also... But when I measured it and if you were to back it in the fronts don't have to be pulled in only the back..Just an idea. Also how long are your ramps?
Used to put upto 4000# pallets of tile on bed tailgate of my F150. U will be fineI doubt the tail gate straps are designed for that much weight
Yeah you can get a rod that takes place of the cables. Sure better then using a trailer
You could try backing it in, if you feel comfortable doing that, then you wouldn't have the weight of the motor on the tailgate. I would still find a way to beef up the tailgate attachment. I think some members on here mentioned they make aftermarket straps that are stronger for things like this.