Went past my local Maplins today and noticed that they have Multi ladders for £49.99. This is what I use all the time when valeting motorhomes and caravans. They can be steps, a ladder or a platform (complete with plates). OK they could probably do with being a bit higher when used as a platform, but then they wouldn't fit in my van
http://www.maplin.co.uk/p/4x3-step-multi-function-folding-ladder-with-platform-356m-n74ka
http://www.maplin.co.uk/p/4x3-step-multi-function-folding-ladder-with-platform-356m-n74ka