Hi Mark,
Concerning the P-47 in Lake Constance:
I was looking again in my documents. I was in contact some years ago with the head of the leading salvaging company in "our" area of the years 50 to 60. So i was looking again in his picture and documents collection.
They have salvaged about 10 ACs in lake constance these days.
I'm sorry,I found a note: P-47 salvaged near Meersburg, Lake Constance. But unfortunatly i have no picture.
I have no information about a known P-47 wreck or a salvage operation in Lake Garda, but as this lake is "behind the mountains" from my bavarian point of view, i'm not sure about.
Another P-47 was found and salvaged some years ago, a diver i know was participating in the salvage. A small lake in Austria:
http://www.tecserv.org/bergung.htm
Regards
Lino