How do I invent this?

When we go camping it’s a turrible ordeal getting our old German shephard, Dakota, in and out of the camper. She can’t do steps. We have a handicap ramp for her at home. But the camper is a different story.
I want to get a car jack and make a crate on top to hold her and simply jack her up and down from the ground to floor level of the camper and vise versa. In our camper we have two entrances so we can designate the back one for her if the jack isn’t terribly portable.
Bring it please! What jack, what crate? How do i create this?
Money IS a consideration.