
what I would do is get a pair of scissors and trim all the fur around under his belly by his willy short. As long as you leave the hair on the sides of his belly alone, then when he is standing you won't even see that it has been trimmed. I did this for a castrated Samoyed belonging to a relative, I cut the hair really short right from the ribs to the sheeth, and the hair around the sheeth also, and all the long bits on the insides of the hind legs too!
As far as him cleaning himself, some dogs are more fastidious than others, and as he is a baby he isn't very skilful yet. I would get one of those baby bath liquids, that are very mild and don't need rinsing for humans. Put some in a bowl, and sponge him down, followed by a rinse off with a sponge of clean water.
I use this on baby puppies, when they roll about in the mess, and when people come to see them to clean their paws. Everyone wants to pick up pups, and a face full of smelly paws is yucky! :D
Barbara and the Grey Curly Tails.