You forget one thing. Trump said...
There is the rub. From seeing his history, the words of Shakespeare come to mind... "...words, words, words.. a tale told by an idiot, full of sound and fury, signifying nothing.." (yes, paraphrased)
Trump's history shows his word is only as good as the moment he is making it and not longer than that. He has never been one to keep his word and as you know as you've said you read The Art of the Deal, lying (for lack of a better term) is a negotiation strategy he employs. He even bragged about lying about building progress in The Art of the Deal to get more funding (a project that went bankrupt after the book was written by the way).
IMHO, his word is no better than if Hillary started saying the same things tomorrow.