I made one last spring and we love it. I was afraid to do the cable support thing because most ramps are rated for a support across the entire contact of the ramp and with the cables, the center would be unsupported. as an alternative, we bought these
BAL C-Series Jackand fastened to a wooden "I" beam made out of a 2x4 and a couple of 1x4's. This supports the ramp across the entire width. Next I made the railings out of pvc electrical conduit which I painted white and the fabric out of a dog kennel mesh sun shade. I did not want to drill holes in the ramp for fear of water infiltration. My solution was to use a 1x4 base for the railings which is simply "C" clamped in place. I made a stair way up to the ramp and have now built a canopy over the top. All of this will fit easily in the garage with room to haul an atv, bicycle and scooter which I have done many times.
I am sure that this would be much easier to understand with pics but unfortunately, I have not taken any. I will be happy to do so and share when the weather warms a little (2 degrees right now).