I don't think they should get UMD beyond what they already do. Maybe give them a single free rank in the skill at 10th level so they can actually use it rather than [Admiral Ackbar]ITS A TRAP![/Admiral Ackbar] if they forget to put 2 cross-class skill points in it since it is a trained-only skill... or just explicitly say that they don't need the rank.
Not sure why you gave them Tumble, since they are generally going to be wearing too heavy of armor to use it. Or do knights get some sort of ability that lets them work around that?