A very worthwhile persuit! I think this list is potentially quite long. Tyler (in "The Early Mandolin") draws attention to the wealth of relatively unexplored early 18th-century operas for more good places to look. Maybe you're just the man for the job!
As it happens I'm preparing "deh vienne alla finestra" from Mozart's Don Giovanni now (on milanese mandolin) along with the aria "Transit Aetas" from Vivaldi's opera "Juditha Triumphans". The latter will be played on a 5-course mandolino. I just met with singers yesterday and both pieces are truly charming.
In addition to the Vivaldi, don't forget "Saper Bramate" from Paisello's Barber of Seville. I played that years ago and remember it as a very lovely tune.
"The effect is pretty at first... It is disquieting to find that there are nineteen people in England who can play the mandolin; and I sincerely hope the number may not increase."
- George Bernard Shaw, Times of London, December 12, 1893