I would move the clipped text out of the URL: have the bookmarklet submit a POST to a draft intake page, then preview and sign only after the user chooses Publish. Measure the encoded URL length if retaining a short-text GET path: a typical Cyrillic letter uses two UTF-8 bytes, which percent-encoding expands to six URL characters. Raising the server limit just moves the cliff. For failures, preserve the clip and offer Copy text rather than silently truncating it.