I have used the two spaced ramp method for the last ten years.
Having measured the distance center to center of the axle spacing on our twin axle van, I now set the ramps out at 41 inches apart from peak to peak. This gives excellent levelling results in the dry.
To aid our winter caravanning, I have screwed the ramps to 65 inch length of builders plank. This holds the ramps firm and stops any sinking and damage on grass pitches. I also have a plain plank the same length (65 inches) to go under the other side to stop the wheels sinking.
For storage on the van, I have fitted a steel "u" shaped loop just behind the back axle, to both chasis rails. I slide the ramps accross the van through the loops and secure the ends with a "G" clamp at each end to stop them sliding out.
A little bit of forward thinking saves a lot of struggling in thewet and windy winter.
Hope you have lots of fun.
Steve L.