Preheat oven to 400°F.
In a steamer pot, bring 2 inches of water to a boil. Add lobster tails to steamer basket and cook 2-3 minutes. Immediately remove from heat and run under cold water to stop further cooking. (It is OK if the meat is not fully cooked at this point. This step is mainly to make the tails easier to remove from their shells. It will finish cooking when we bake the pineapple boats later). Set aside.
Slice the pineapple (including the top) in half length-wise. Cut or scoop out the flesh, leaving a shell about ½ inch thick. Set hollowed-out shells aside. Remove the tough core from the pineapple flesh and discard it. Roughly chop the remaining fruit and set aside in a bowl.
Peel and chop the garlic, shallots, turmeric, and ginger. Remove the outer few layers of the lemongrass. Trim off the tough upper parts of the leaves, and about 2 inches from the bottom of the stalks. Finely mince the remaining parts of the stalks. Combine with all remaining curry ingredients except the coconut milk, and puree in a blender or food processor until a smooth paste is formed (add more water, a little at a time, if needed while blending to achieve the desired consistency).
Heat a skillet or saute pan over medium heat, and add a little oil (no more than 1 Tbs). Add the curry paste and cook for 2 - 3 minutes. Stir in the chopped pineapple and any juice that has accumulated in the bowl. Simmer 5 minutes, stirring occasionally. Turn off the heat, then stir in the coconut milk.
Remove the lobster tail meat from the shells. Roughly chop the meat. Divide the cooked rice evenly between the two empty pineapple shells, and pack down lightly to make a level bed. Sprinkle the chopped lobster over the rice. Spoon the pineapple curry mixture evenly between both boats, making sure to completely cover the lobster and rice.
Wrap the tops of the pineapple in foil, then transfer both boats to a large baking sheet. Place in oven and bake at 400°F for 30 minutes.
Remove foil from tops before serving.