If you write horizontally, it belongs to modern format and must be punctuated. At least 48 words. So you can't sign it. Unless there is a special place to sign, it is not feasible to write horizontally.
Write vertically, from right to left, without punctuation. There are eight diamonds left. If it is a hard-pen regular script, it can be signed in words the same size as the text, and it can be signed: Gengzi Winter Moon X. If it is calligraphy, the inscription should be smaller and not restricted by the grid. Write the full amount: A book entitled "The Winter Moon of Gengzi ⅹ" written by Meng Haoran passed through the village for the elderly.