We have the four-step RV steps as well. I plan on buying two different sizes of RV step stabilizer jacks to put under the bottom two steps. I figure that will help stop the flexing that is done when my 220 pounds hits each step and lessen the strain on the rest.
I just haven't decided whether to put one stabilizer jack for each step or two jacks. I may start with one each in the centers and if that doesn't suit me, I'll buy another set and place one on each side of each ot the bottom two steps.
Here is a link to some at Camping World, although I think I've seen similar ones cheaper on Amazon.
http://www.campingworld.com/shopping...tep-jacks/5416