A change of clothes, a few pairs of socks and underwear, small tent and sleeping bag, and a little food. What more do you need? You could fit that all in one pannier. My last multi-day trip was with about 13 lbs of gear and I felt that was too much. But I also spend months at a time traveling other countries with nothing more than my trusty 24 liter Deuter backpack loaded to about 7 pounds. Once you take a trip with nothing more than bare essentials, you realize how very few things are actually bare essentials.
I understand not everyone can afford one of those fancy 1/2 pound ultralight tents. I can't either! Do the best with that you have. But try to keep your weight <15 pounds (excluding water) and you will have a very enjoyable trip! And no traveler ever said, "I really wish I would have brought that fourth pair of jeans!"