"Other productions have had them getting wet or mud caked."
I don't know if you are referencing it specifically, but Robert Lepage's National Theatre production in 1993 (ish) set the play on an almost bare stage caked in dry mud. As the show progressed it gradually got wetter and sloppier and by the time Theseus and Egeus discovered the lovers in the forest, they were covered in mud. Before heading back to Athens, the US wall rose, revealing a waterfall, and the quartet stood under the pouring water getting cleansed. It was a deeply beautiful and moving image.