What's the actual weight of your car? I think the liftgate issue is the weakest part of your plan. I work on a number of those things, and they're designed for load center much shorter(closer to the truck) than a car. Pallets and the like.

Is it air ride? I would look at ramps, as opposed to the liftgate unless your car is under 3000lbs or so, you're just asking for catastrophic fail otherwise. S/F....Ken M