Okay, I have played deep into a game in 6.2 and lurve it, but a few things.
1) Spies are useless other than as relationship counselors. I did a few tests as I generally just siege over time rather than storm a castle, since I think the initial assault stage (text) doesn't take surgery into account. So, 20 spies v. Tyrosh, can you get in? Can you nerf the food? Can you make them puke on the well water? Let's see...I had 3 spies left at the end, one burned the food but died trying to poison the well, and the 3rd last spy managed to get in and poison the well.
That's a little harsh. Maybe you can make a charisma based espionage skill that boosts their success chance by a certain amount, because they seem to be around 1/5 for each task of getting, in and then another 1/5 for actually doing anything, and then like a 1/10 chance for being discovered even if they are not doing anything. So...10 in the skill gets you to like 1/3 or 1/2 for each step? What do you think? Because now I just use them for getting relationship boosts.
2) Most of the castle chests when you take a city are empty, even KL, I guess I could do this myself, but maybe a Kingsguard armor or something in there, maybe an arming sword with slightly better stats in some castles, or scimitars down in Dorne or something, even if it's vendor food, it's nice to see something in there.
3) Camp defense, maybe have the enemy spawn in all their troops, in, I don't know, the same rate as your reinforcements spawn in, as it stands it's a farm renown situation.
One note to get the Kingsguard companions and Jon snow, I think you have to be in a state of aggression or war with the Lannisters or the NW to get them, and I think Jon has to be a Lord, so after Mormont, correct me if I am wrong there, I was not in a state of aggro with the NW when I tried several dozen times to kill Harma Dogshead who had him captive while Mormont was still alive. If you are not in a state of aggro you just say bye! And in Jon's case, I didn't get any chance to grab him. So, try being aggresive but not at war with the NW.
For strategy, well, you have several priorities, because you have a chance to strike at KL between turns 50 and 96 like you will never get again. You need a good 270 or so, and will likely need to beat a lord or two. Have a fun inventory of food, donkeys that increase your inventory capacity are a bonus, send out foragers, and settle in. If you have any companions that get pissy about running out of food, send them on a find support mission or something. Critically you should have 30ish right to rule by the time the siege ends. That's about 2-3 weeks on KL, so you can send a few companions out for support and get the required right to rule by the time it's over.
The reason for that troop number is so you can fortify your camp and build defenses. Fortified camp defense is hard against the Reach and the Westerlands because of their huge number of Cav, so you have to be quick.
Tell everyone to stand because they start by being on charge for some reason, so your side projects (your Bravosi and camp followers), will be charging into combat and getting ganked.
I am not sure how many different siege camps there are but if you are fortified, you will have stakes in the ground all around you, you can clip through them but the AI can't without getting stuck there for a long time. So, have your infantry, spearmen and dismounted cav move towards the break in the stakes where the enemy will pour through, stand closer x3. Archers stand closer once and up on the hill overlooking the approach and the hopefully wall of enemies coming in there.
My only problem with the camp defense is that in big battles, it's not continual, 50-75 or so men at a time, then you have to do it all over again, you farm crazy amounts of prestige, like 500 or so from a really big one, and with the memory leaks in this game, just go ahead and save and exit after that battle, because you just ran like 20 versions of that battle.
For fighting the desperate out of food defenders, again, be quick, your troops are charging, stand your ground, send the infantry out, stand closer, there's no cav in this fight, and cav and spearmen out to shield the archers, who you can try to put in a good place. I've lost 10 or so men here, but I mostly play as Qyburn or Sylva to this point for a great level of surgery. I give them a crossbow or short bow, take your pick and go to town on the enemies, I've had them around level 15, especially if I get a good camp defense, short bow on Sylva and 3 large stacks of barbed arrows, plink, plink, plink. So, I have a high survival rate.
After you have KL, you may or may not be at war with the Westerlands...strange I know, but I was not the several times I have now done this, I have been working on optimizing my strategy, everything is based on this, heck, I've turned Pod into a surgeon because I did not find Qyburn or Sylva yet before. Stormlanders are the best, but it's very dangerous to go down there before you have say, 50 or so tier 3 infantry (peasant, levy, militia), because Robber Knights are suicidal buggers and will attack you even when you have 100 tier 3 infantry. Annoyingly they will actually kill a few, but then you have 20-30 Robber Knights to sell to the NW, so it balances out.
Stormlanders get a nice shield, decent armor at tier 3, and that's important because unless you can afford Syrio you are likely to be sporting a mix of Levies and Militia. Stormlander levies get a shield at least, and they have a low hanging Archer, and so does the Reach, the Reach...nope, their levies don't get shields, they are trash at this stage, after you get KL and can breathe a bit, go to town on them, good troops, but I still prefer Stormlanders.
Why is Turn 50ish so magical? The Riverlands join the war against the Westerlands, and most importantly around KL you will have Dragonstone, the Stormlands and Riverlands all patrolling with armies keeping the Lannisters off your back.
At turn 96 the Reach joints and the Riverlands can't handle that, the AI sucketh against huge Cav armies. As for you fighting the Westerlands, look for bridges, and watch them burn.
And lastly, I love this Mod, great work Produno.