I'm not certain how it works in 7th Ed. (still haven't played a game or sat down with the rules yet) But it used to be that if the transport has not yet moved, you could disembark, move then charge. If it had moved, then you'd have to suck up a round of shooting yes. So with careful maneuvering you could get the small unit with Yarrick and priest into combat while avoiding the everything but overwatch. Assuming it still works this way anyhow.