Hideouts aren't really fine.
Hideouts don't really work properly with the size of the bandit mobile parties that infest them. I mean in terms of troop placement. You can see what it looks like when it's working properly because there are positions where they have camps, if you have good sized parties in the hideout you see people sitting around a campfire, a guy patrolling, a couple guys sleeping on a bed, some guys standing around some stolen loot. It looks like it is intentional.
When you have 3 mobile parties that are 30+ troops, it doesn't look right. Instead of these little camps of guys that look intentionally placed with their unique idle animations, you get a crowd of troops spawned in because the preset locations are filled up and it just spawns a clump of them in the general location standing at ready.
My opinion is that a max of about 10 or so troops per bandit party is near about what the game is intended to support. This is still a challenging encounter, because that's 40 bandits. This makes good sense because you're allowed to bring 9 troops I think.
The way that the bandits spawn in is that there's various different area markers, which are little camps, or little rooms, or caves, or whatever. Within those markers are standing points where they have their predefined positions. In the case that there's no more bandits than standing points, you can have some kind of cool encounters, generally you can as the player position your own troops to lie in wait, and shoot an arrow into the room, maybe even taking down 1 or 2 bandits as they charge towards you, at which point you retreat back to your formation and let your ambush take a very advantageous fight. Then you move to the next room and do the same. So while you're fighting with odds at 4 to 1 against you overall, each combat is about 1 to 1 with an your party having the advantage against the troops that are generally sitting or sleeping or not paying attention. This is actually a pretty fun experience though a bit repetitive.
On the other hand, this whole dynamic changes when the number of bandits get too high. The whole hand crafted system of bandits appearing to go about their business while you sneak in on them disappears, because all of the excess bandits just get spawned in a clump standing ready waiting for you. A couple of other things happen, one is that where there might have been two rooms that previously you could sneakily engage separately, now because there's so many bandits engaging one will alert the other and they'll all come after you. Next, where you were previously fighting a number of relatively even battles with an advantage because of surprise, but without being able to heal up, now you are fighting a couple giant battles where you're vastly outnumbered.
I think that maybe there was intentions to change the way that roaming bandit parties left the hideout, for instance, or maybe at one point in development it did work differently but now it's changed. Maybe bandit party sizes didn't scale up as high as they used to but they changed it. But the bandit camps are absolutely designed to hold a maximum number of troops, and if they DO hold that number of troops, the act of ambushing the hideout does look and play much better and is pretty fair.
The other big deal is that you don't get to choose your party to attack the hideout, and that while you can influence it by changing the order of troops, you always must bring all of your clan members and it doesn't entirely respect the party order. So you're forced to bring your surgeon even if they're not really the best fighter, and you might end up with a couple of recruits.
I've got some other issues with hideout and bandit/looter behavior in general, but that's more about how they work on the map, and less to do with how attacking the hideout is, and in fact this is probably much more related the the reason WHY hideouts have so many bandits in them, because this is directly related to the number and size of bandit parties that have entered the hideout map location, when they leave, how many get generated, etc.
But the result is, 40 bandits on the map is OK. 40 bandits in the hideout is OK. 3-4 parties of 40 bandits in the hideout is a problem. Plus it would be good if bandits on the map made better decisions, but generally units on the map can make better decisions.
However, the alternative of bringing 100 units to kill 100 bandits in a camp also is terrible. 100 vs 100 battles in a town or the open field is good. Bandit hideouts are a specific type of gameplay, where you should be attacking with a small team of your best soldiers, setting up ambushes, taking them unaware, and cleaning out a larger number with a smaller party. Sometimes you get to have that experience and it's fun. Sometimes the bandit camps are empty and you just fight the leader and his men and it's much less fun. Sometimes you end up finding a camp with 130 bandits and it's kind of impossible.
You can even things out a bit by hanging around the base until some bandits leave, you can also enter the fight, kill a few and then retreat and come back. But these aren't really fun solutions. What would be fun would be that when you find a bandit lair that you can sneak in with your SEAL team and take them out in their sleep. There's also nothing wrong with waiting until it's a bit less defended, but the way the bandit map behavior works they're just going to stay in the hideout for a very long time, and it's not worth it to try to find an advantageous time to strike. Nor will they ever split a party up to leave defenders in the hideout.