I don't know if that will help or not since it's the distance between the bolts that is causing problems and I have tried several other years kx250 and they do not fit the holes are closer together on some years of 250 but their airbox may be the same I'm not sure.
This is the UFO it's for a 91-99 KX250 but bike bandit had it listed as fitting the kx500 but as you can see it does not but the airbox may be the same size at the k5 it doesn't matter because the bolts are so far apart.
This acerbis is for a 03-07 kx 250 but cheap cycle parts had it listed as fitting my kx 500 but as you can see it does no and the airbox on the 250 may be the same but the bolts are farther apart and both of these kx250 mud flaps are too narrow by a lot.