It probably depends on how big your crew is. Gary Maskiell sailed "Perfect Score" as a sloop with a centre mainsheet cleat on the beam. He had his son crewing, who was probably about 12 or 13 at the time. He won the states so it can't have been too much of a hindrance.

You can also put the ratchet block on the boom and run the sheet from there like I do (if you don't need a cleat). Then there's nothing in the crew's way.