Hi Kevin, you only need one ramp, I use one similar to this in the link
https://www.amazon.co.uk/Towsure-Chockma...aravan+leveller
This one has a small tongue at the front which stops the ramp been pushed away when the tyre rolls forward, it is also a graduated slope with a stop which makes it easier to roll up, I do use mine quite often.
The one in your link has different graduations which needs more effort to get over each level.