You can sand and paint over powder coat, it would be very difficult to color match for a touch up though. A crack will show up just as fast under powder coat as paint. you just have to chip it off before you can weld it, then there's the issue with matching the color again. But then, it may never develop a crack. It's not a big deal, just something to think about if your going to ride it off road and get chips and pits.