Hornblower again laughs in the face of attempts to prevent him from hiring officers.
If you capture an enemy ship which then surrenders, you can offer the captain a new job. Also, Fred Bob and Rys Bloom are available from their respective side quests.
It occurs to me that blocking hiring of officers may be the wrong approach anyway. I've now completed the whole story a second time with additional officers. The only problem comes if one of them is active when he should not be. The one incident I remember from last time was during "Tunnel of Trouble", you've just found the tunnels to the pirate settlement and naval academy, you walk from the academy to Smug Larr's house, Sharpe follows you and talks to you when you get to the house. If I had an officer active, Sharpe didn't say his piece and Pellew didn't show up inside the house. Sharpe wasn't assigned as an active officer at that time, he followed me and talked of his own initiative. But the game adds numerous characters to your Passengers list and sometimes makes them active, and I suspect the game will also break if they're not active when they should be. So, other than hiring so many officers that your Passenger list is full and the story can't add any more, it's not hiring officers which is the problem, it's messing with the Passengers list. Perhaps disable the "Passengers" tab from the interface screen while the story is active?
You asked for a saved game from just before the story ends, so here it is. There are several problems with transitioning to free-play and one of them will be obvious as soon as you load up this game.
During the action at Guadeloupe you change identity several times so that you can observe some conversations which do not involve Hornblower directly, and you are not returned to your correct identity, which means you arrive at Bridgetown as Lt. Bush. There's an easy workround, which is to rename yourself back to "Horatio Hornblower" and change outfit back to that of Commander Hornblower.
So you go into Mrs. Mason's house single and in command of heavy sloop
HMS Hotspur, and leave the house married and in command of 6th rate frigate
HMS Atropos. I don't know how Mrs. Mason managed that, but it certainly wasn't the navy's doing because you haven't been to naval HQ, nor has any midshipman arrived to give you new orders. Talking of midshipmen, numerous characters from the story are still in your Passengers list, including Sharpe and his men, Teresa Moreno, and several naval characters. One of these is Archie Kennedy, who is literally a dead man walking because he's supposed to have died at the end of "Mutiny". Meanwhile, the quest "Old Friends - New Enemies" is still open.
Several side quests are available, but most don't work properly. Those which I have checked:
Help the Boatswain: Fred Bob does not give you the letter. So although Senora Alencar is present in San Juan church, she won't let you help her.
Help the Church: the assistant priest is present at Bridgetown church. If I talk to the priest in Kingston, he asks what I have found out and I can only reply "Nothing so far". It's as if the quest has already started, though nobody in Bridgetown has anything to say which will advance it.
Patric and the Idols: works for the most part, though you can't say anything to Lucien Bescanceny except to comment on his drunkenness. In fact you don't need to visit him at all, as Patric reacts as if you've already asked Lucien about the idols. You can then conclude the quest by speaking to Harduin Aufort and then finally again to Patric.
Saga of the Blaque Family: works as intended.
Saving Toff's Daughter: Toff Oremans is present in Kralendijk tavern and you can start the quest. When you go through the port gate there is no option to go to the pirate ship, all you get is a repeat of the last thing Toff said. If you go to the governor first, when you go through port gate you get a repeat of the last thing the governor said instead.
Sink the Pirate Corvette: works as intended.
Woman Who Lost Husband And Son: works as intended.
Cargo for Thomas Reilly: unavailable even though France is neutral to Britain at the end of the "Hornblower" story.
Elizabeth Shaw's Disappearance: unavailable, Governor Shaw only gives standard ship-hunting quests.
Strange Things Going On in the Caribbean: unavailable, no women standing outside Kralendijk residence.
In addition, the quest book does not work properly with any of these quests. Even the ones which otherwise work as intended. The top quest in the book (the still open "Old Friends - New Enemies") becomes blank, all the rest are out of sync so that clicking on one quest shows the entry for a different quest one line up, and there's a blank line at the bottom of the book which you can't click on.