To explain better the remark about "canonical" clauses: Huddleston & Pullum are saying that for the most part you don't speak of an "indirect object" unless the sentence has two non-subject arguments. That's because English is not very permissive about omitting arguments. If a verb sense requires certain arguments, they normally cannot be omitted entirely. But suppose you have a verb which is normally ditransitive, and it has a sense requiring only one argument, marked like an indirect object (a prepositional phrase)? In that case the sense would normally be classified as extended intransitive rather than ditransitive. (e.g., get in The cat got under the table). So you are kind of blocked from finding such examples.