Preheat a smoker to 225°F. Line a rimmed baking sheet with foil and set a wire rack on top.
In a mixing bowl, combine the ground beef, egg, breadcrumbs, onion, Worcestershire sauce, salt, and pepper. Mix gently just until combined, then shape into a compact loaf about 8 inches long.
Lay the bacon slices side by side on a piece of parchment, slightly overlapping them. Place the meatloaf in the center and wrap the bacon around it, tucking the ends underneath. Set it seam-side down on the rack.
Smoke the meatloaf until the center reaches 160°F on an instant-read thermometer, about 1 1/2 to 2 hours. Transfer it to a plate and let it cool until no longer hot. Refrigerate briefly if needed so the pastry stays cold during assembly.
Heat the oven to 400°F. Lightly flour a work surface and roll the thawed puff pastry into a rectangle large enough to wrap the loaf. Brush the center of the pastry with the olive oil, then spread the Dijon mustard over it.
Place the cooled meatloaf in the middle of the pastry, bacon seam-side down. Fold the pastry over the loaf and pinch the edges to seal. Trim away excess pastry, then place the Wellington seam-side down on the foil-lined baking sheet.
Brush the pastry all over with the beaten egg. Cut a few small slits in the top to let steam escape.
Bake until the pastry is puffed and deeply golden, about 25 to 30 minutes. Rest for 10 minutes before slicing so the layers hold together.