Wow, I'd better edit that post. I just looked at the listings again and I realized that for the rear panniers, the 18.5L capacity is for each of them. Total 37L. Also, the waterproof front panniers are also rated by capacity individually, so total capacity is 28L. The non-waterproof front panniers don't specify, but they say 10L and I think that's each of them, so 20L total. So any of these panniers by itself would have all the space I need.

And I'm not carrying a tent.