Licenses for federal crane certification starts at anything over 2000 there are a few States and municipalities that have a different weight limits (or in one case lifting height) that may apply for their own licenses or permits. As to having a crane rerated it has to be rerated through the original manufacture of the equipment. I cannot speak for other manufactures but we do a rerate kit for every crane that we have built. It is a fairly easy install and it limits the load that the unit is able to lift and it also comes with new load charts and operations manual plus it is registered with us as a rerated crane incase there is ever a question on it. This rerating can also be reversed in the future if your operators get their certification.