It wouldn't be full mainsail. It would be a mainsail reefed down for the wind conditions. In sea-states where you're worried about creating a slick, you'd typically be fully reefed or flying a trysail.
That makes sense. Thanks.
Still, it seems strange that you'd heave to with main only as that seems to put the majority of the pressure at the stern of the boat - leading to more weather helm potential.
I'll have to try it.