Interesting Art. I would think a wood ramp built to get over your stoop tapered on both sides would work. Very rough paint drawing attached. On a similar note, I picked up a Craftsman ATV lifter today and am trying to figure out the best way to mod it for my needs.

rough ramp (resized).jpg

OK Art, while I was working in the garage tonight trying to figure out my latest project, I pulled out my car ramps and pulled them apart at just the ramp part, (there is another whole part where the tires sit once the car is elevated). I did not measure my stoop or car ramps but your stoop and mine look similar. So maybe these car ramps and some wood could fit the need. Possibly plywood instead of just that 2x4 but I think you get the point. These ramps are called Magnum ramps and they are made in the good old USA.

magnum ramps (resized).jpg