I did a duck this past weekend on the roti. My method was dry brine for a couple days with kosher salt sprinkled over the bird, then cook with cut limes inside. Key was to poke several holes in the skin to allow the fat to drain into the pan, where I placed a few red potatoes to cook in the duck fat. Grill ran around 375 for 90 mins or so. Skin was nice and crispy while meat was still juicy. Was a delicious Sunday meal!