McDude,
The old postcard may in fact be an idealized picture or the lake could be Winnie in the distance.
The location of the Camp School is on the north part of Rust Pond(the immediate water). Wentworth would be in the opposite direction. The part of Winnie opposite the School would be South Wolfeboro Bay which is in a deep hollow. Maybe it could be a section of the lake by the Varney Islands. The area years ago was cleared of trees which today block the view.
The map is accurate in placement but greatly out of scale.
