I saw pics on wakeworld one time, of a helicopter following a tow boat, and the guy jumping the wake (at least in the pics) looked like he was within inches of the rotor.
Back in the day, Bob Wills was flying his hang glider filming for a Jeep commercial at Escape County, the helicopter flew over top of Wills and drove him into the ground.
Saw that on the news this morning. First thought was - looks close vertically, but for all I know horizontally they could be 50' apart. Who know's, maybe it was real close...