Make sure to select the sniper as your only weapon on choice. When you start the level 'A Vintage Year', head towards the waterfall. Hide your sniper somwhere then sedate or poison the guard here and take his clothes then go back to the front gate, enter and head into the Wine Cellar. Wait until the guard here goes downstairs before rigging the rope pulley with the bomb. Head downstairs and to the right and hide behind the large object that has purple stuff in it. Wait here crouched and with your detonator in hand until the son enters the area under the hanging barrels. Detonate the bomb, unequip your detonator then get out of the wine cellar quickly and go back where you left your suit. Change back into your suit and unpack your
sniper. Check your map and wait until the Don heads towards the middle room (he is on the right). Enter the sniper scope view and aim towards the second balcony. Wait until the Don steps out and shoot him in the head for a one-hit killshot. Pack your sniper away, head down the path, go round to the seaplane and escape.