I personally like the idea of a drop bed trailer, they pin the back to the sides, unpin and ratchet the front down and then the back goes down. Must be unhitched from tow vehicle.
or a trailer where the rear axle is unpinned and rotates up to drop the bed to the ground at the back. The cool thing about that is you don't need a jack to change the tire.
For a safer, lightweight ramp I would suggest a metal frame with expanded metal welded ontop.