What are the pitfalls of sleeping in the open, as vividly described by the narrator in Jerome's Three Men in a Boat?

This topic is addressed in Chapter II. The three men (J., George, and Harris) have already decided to take a boat trip along the River Thames. Now they have to decide if they should camp out or stay in inns along the way. J. and George vote for camping out. J. paints a restful, bucolic scene of how wonderful it would be to have a camp site where they could cook and eat a leisurely supper, smoke their pipes, and lie there under a bright and beautiful moon. Harris stops him by asking, “How about when it rained?” Well then, the story changes dramatically. Everything is wet, including the food and the tobacco. Two people try to put up the soaked tent in the storm, and they get tangled up in it instead. They finally meet with some success – only to have the tent fall down on all of the sleepers in the middle of the night. Thinking it over, the men decide this time to camp out on good nights and to find an inn on any rainy ones.