The Official Website for Bigfoot© Hydraulic Leveling Systems
Highly recommend. I had them on our 32 foot super slide class C. I talked a friend into them as well.
If you're handy with a welder its about a days worth of crawling around under your RV. If you want to take a trip to Michigan they offer reasonable installation and it takes them about a half day to install.
I went all over the country with them and never had an issue. If they still offer a wired system I would do that over a wireless.