Adding a retractable step... what does it attach to?

[Guigsy]

Our coachbuild has quite a big step up through a fairly narrow doorway. It's not always the most elegant of moves when boarding or alighting. We normally just put a folding step outside, but it's not ideal. I was thinking of adding a retractable step, but I don't know what to attach it to. The base of the first step inside appears to just be a piece of double thickness moulded plastic. As far as I can tell, it's built like half a tub, with the lip around the upper edge supported at the inside floor level. Is this common? Is it possible to fit a retractable step to the underside of these?

Thanks.

 

[68c]

You will need to fabricate a steel mount frame. Will have to be strong as it is surprising how much weight is put in a step on stepping down. My van has the low level Alko chassis with a double floor, the step is bolted through the lower floor through 3/4" plywood. After twenty years it has started to flex so I have added doubler plates.