Preheat your smoker to 250°F for indirect smoking. There are many options for the wood including hickory, mesquite, cherrywood, pecan, oak or maple.
In a large bowl, add the ground beef, onion, garlic, eggs, breadcrumbs, salt, pepper, sage and 2 tablespoons of BBQ sauce. Using a large spoon or your hands, mix just until combined.
Place a large piece of parchment on a work surface. Turn the meat mixture onto the parchment and form into a oval or log shape using your hands, smoothing out any bumps or imperfections. (See notes if you want to make it bacon-wrapped or stuffed).
Transfer the meatloaf to a grill tray or basket (or make your own using aluminum foil). Insert the probe of a wireless thermometer into the middle of the meatloaf (if using).
Place in the smoker for about 2 hours. After about 1 1/2 hours, brush with the remaining BBQ sauce to form a glaze. The meatloaf is done when the internal temperature reaches 160°F.
Remove from the smoker and let it rest for 15 minutes before slicing.