Poach the pear in lightly salted water with a splash of port until just tender. Cool, peel, core, and cut into four wedges.
Wrap each wedge with bacon. Grill or pan-sear over medium heat until the bacon is crisp and the pear warmed through.
For the mousse: blend gorgonzola until smooth; fold in softly whipped cream. Pipe onto the crackers with a star-tip to create towers.
Whisk vinegar, Dijon, and port; drizzle in olive oil to emulsify. Season to taste.
Plate warm pear wedges beside the gorgonzola towers. Spoon vinaigrette over, then garnish with walnuts, grapes, and chives.