loony
I had something similar happen in about the same area, but in my case there wasn't any other boat even close!
I was moving along at a fair clip and a large wave came out of nowhere. Before I could come off plane I actually buried the bow and wound up with a solid wall of water going clear over the bimini top on a 24 ft cruiser.
I wish I could have seen it; it must have been impresive!
To this day, I have no idea of where the wave came from.
Silver Duck