Instead of Passages South, I'd suggest Bruce Van Sant's "Tricks of the Trades" -- which speaks to running your power boat as if she were a sail. Those on power boats tend to go from point A to B, whereas tacking is often a far more comfortable ride.
His Tricks book (the information within the pages) is the same as that found in Gent's Guide. As a matter of fact, I've got an old copy of Gents (4th Edition; #10 just came out last year) -- I prefer Tricks of the Trades as it doesn't have the specifics on island hopping. It's easier to read.
If you'd like Gent's #4, I'll be happy to send it to you. I have 10th and it (#4) is a spare sitting on my shelf. Side Note: Were I to do it again, I'd buy the 9th edition as it's spiral bound and lays flat.
And work on your lady in short hops, marina to resort marina. There's not much a gal would dislike about a marina with a swimming pool, bar and lounge plus a restaurant. And I know few men who object to a lounge, entertainment, with delicious food served at the tables by waiters and waitresses.
And the kids will find a video room too or things to occupy them out by the pool.
You're ot the first who has had optimistic plans go awry. You can fix it I hope. The IP's (sailboats at least) are wonderful. Friends owned Kairos and theirs was truly a treat. I'm sure yours is likewise as nice inside, and out.
Good luck with your lady.