Three years ago my co-pilot could no longer climb the steps into our rig, so I did some searching and found a lower cost solution in this product: http://www.mobile-lifts.com/motorhome-and-rv-lifts/
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Click LinkIt arrived in two parcels and only took about a 1/2 day to install - the most time consuming was running power to it. We too were delighted to again have the ability to use the RV together. Total cost was less than $2K. N.B. As the lift operates on the outside wall, I needed to build (from 3/4 plywood and "L" Aluminum pieces) a removable flat panel to fit over the inside entry steps - like the one in the picture). It also adds that bit of floor space so one does not unexpectedly step into the stepwell.