Your writer’s block ends here. I have thought up the rest of your novel for you, and you have no time to disagree. You will either write this ending and make it your own, or have no Huck Finn at all. So, on this note, here are my thoughts.
After you have the steamboat break Huck and Jims raft, the only option to continue an adventurous novel would is if you separate the two characters. Jim doesn’t know how to swim, so he gets pushed down one direction of the river. Amongst almost drowning, Jim is rescued by some men and women. These people end up being Quakers who take aid and take in Jim. Now is Jim in luck, because not only are these Quakers superbly nice and helpful feed and clothe Jim, but they also run an underground railroad for runaway slaves. At this point, Jim is confronted with some options. He has the opportunity to escape to the north and be the free man has always desired to be, or he can wait and try to find Huck, his dear friend and accomplice who helped him get where he is and is most likely in some trouble himself.
At this point, the focus is moved to Jim. While Jim goes in one direction after being separated, Huck goes another. He awakes to find that he has washed up on shore, and with clothes soaking wet and minimal amounts of energy he lies on the river bay under the steaming sun while waiting for his clothes to dry. He then begins his journey by foot and tries to find a town. This he does. It’s a small town where everybody is close and knows each other. Within hours of coming upon this town, all of the town’s folk know Huck by name and treat him with the utmost care and respect. Genuinely nice people. The town decides to keep Huck with the Whitleys, a family who’s not too rich nor too poor. They are the nicest a family can be, without being too proper, or too drunk. This is the ideal family to Huck, as he fits in perfectly and feels at home. That night the town is roaring and theres a light coming from outside Hucks window....