Hi Radzig: My 2-pennies worth…
If you choose to simply untie Hans, wait until night. Even better, use the time to do some more hunting and only head up to the camp when it starts to get dark. At night, one Cuman will be sleeping and the other sat at the fire. The one at the fire will change sides at regular intervals. Sneak close to the camp behind Hans. Wait until the fire guy moves and is facing away, sneak in and untie, sneak out.
For a decent stealth outfit, everything you need can be obtained from the 3 bandits you fight on the road to Skalitz - from the last 2 actually. Between them, you can get the Padded Dark Coif, Ordinary Tarred Jacket, Noble Boots, Hunters Gloves and the ‘quiet’ variant of Patched Hose. Not only does this make you look like epic Scum of the Earth it gives you low noise and visibility. For a decent weapon, the Skalitz Bailiffs Shard is as good as it gets for one-handed. Steal a shield from Talmberg to go with it.
For the combat route, I think it’s still best to wait for night to aid the initial takedown. You really don’t want to fight both at once. The archer is usually my first target - unlike the Cumans in road ambushes with Dogwood bows and hunting arrows, this guy is the real deal. He has the proper Cuman bow and a quiver full of wounding arrows. He will hurt you a lot. Melee guy isn’t so much of a big deal without his archer buddy backing him up.
I reckon the best approach is from the west side of the camp - it gives you the option of sneaking up behind the guy at the fire when he is facing away, or sneaking over to the tent where the other is sleeping.
If you don’t have Stealth Kill at this point, close range archery is probably a better option than trying the knockout lottery. Don’t bother with fancy headshots - the Cumans have helmets and mail collars. Aim for the body, where they have no armour. Another reason to target the archer - he doesn’t have a shield strapped to his back. You can sneak up close and shoot him in the back with ease. If he’s in the tent, even easier.
Then melee the other.
In melee, just be patient. Even melee guy isn’t so great. Stab at the face, slash low at his unarmoured body on the side away from his shield. Remember your blocks and follow him up when you get a chance. Back off when you need a rest and stab at him when he comes chasing you.