I often think that people with smaller hands have a better grasp of piano technique. Look at all the childhood virtuosos playing works that require bigger hands. How do little hands play big things? By eliminating all unnecessary tension. They tend to stretch less and move more, meaning instead of "thumb under" they use the proverbial "thumb over" technique to a much greater extent than many of us appreciate.
So, while attempting to play this legato, do not overtax your body. It is possible to injure yourself, or at least cause some temporary soreness. There is a certain extent to which smaller hands can play this legato, but understand that the size of your hands may limit you in that respect. Accomplish what you can without straining your hand, and then use the piano to aid you (left hand octaves, pedal). Piano technique, of course, is not limited to what your hands do, but to all elements of the piano, including pedaling.