I've never done it, but it shouldn't be that hard. If you are going to weld a piece in to extend the length you need to be pretty handy with a welder. If that's not the case you might consider finding a section that will slide on over your existing tongue(just big enough to slide over it). Make this section three feet or so longer than you want to extend, to allow your existing tongue ends to slide inside for strength. This would take some(most) of the weight off the welds. Welds will still have to be able to endure the forward/back pressures.