It took me a day, I'm sure it can be done quicker but I took my time as it was a brand new van. You need to drop the fuel tank to do it, my one is a 4motion also so was a bit tight getting the ones above the rear diff done.How long would it take to remove the rails from start to finish?
Other than that nothing too complex to it, there are holes in the chassis cross members where the holes need to go.