This is one reason I'm so concerned about lack of proof of payment in AMP/LL's implementation of static invoices. How do you build a decentralized layer 3 without being able to prove that things happened on layer 2, without "hooks" into layer 2?

Anyway, the best hackery of preimages I've seen has been done by @03bcf114f6 on squeaknode and he ran into some pretty big hurdles.