Preheat the oven to 225 degrees F (see notes), and adjust a rack to the center.
In a large mixing bowl, combine the 4 cans of beans, draining only about ½ of the liquid from each one before doing so.
In an approximately 5 quart Dutch oven, or other oven proof pot, add about ⅓ of the bean mixture. Then as evenly as possible, drizzle about a third of the ketchup, half of the molasses, and 1 tablespoon of the Worcestershire sauce on top. Next sprinkle about ½ cup of the onions. Add one layer of the bacon on top of the onions, so that the ingredients are covered completely. (You can cut the bacon strips in half if necessary.)
Repeat the above layering process two more times, but on the last time, there will be no molasses.
Cover the pot and place it on a baking sheet in the preheated 225 degree F oven for 7 hours.
Remove from the oven, add the knockwurst and then bake for 1 more hour.
Notes
* I'm sure you could also make this recipe in a slow cooker. Believe it or not, I don't own one. (Gasp!)