Sort beans in a large bowl. Rinse in a colander. Then, put the beans back into the bowl and cover with cold water. Let them sit overnight.
In the morning parboil the beans in 8 cups of water until the skins crack when blown on, drain and save the water. This takes about 30-35 minutes.
Chop onion and slice salt pork into 4 equal chunks. Set aside a few thinner slices to top the beans with.
Mix the maple syrup, brown sugar, mustard, ground cloves, salt and pepper together in a large bowl. Then mix in 4 cups of the saved cooking water.
Put some of the onion in the bottom of a Dutch oven along with some of the salt pork. Add beans to about 1 1/2 inches thick and add the remainder of the onion with more salt pork saving some strips of salt pork for the top.
Add the remainder of beans, and pour the mixture of sugars and spices over the beans until covered. Top with the reserved thin slices of salt pork.
Cover the pot and bake at 300 degrees for at least 7 hours, adding more of the saved water as they cook to keep the beans from drying out. You can leave the top off for the last 30 minutes to brown the beans further, as long as they are fully cooked at that point.