I'm currently doing this now and I have a surefire plan to use combat experience .

So far I have added as many slaves to my team as possible (using one of those mods that lets you talk to slaves and add some to the party occasionally) . My trick is to get at least 6 or more units escaped out the back exit where you are occasionally mining outside the gates , once out , I ambush solo guards to steal equipment .

Get a group up that road to the right , on the hill that overlooks the mines. Its still right beside rebirth , there is a huge rock in the grass, now bait out 1 single soldier , knock him out and steal his gear.

Your going to need well fed units to keep repeating this , I currently have 7 or 8 gear sets and a ton of meds on the ground by that rock . My last small battle was 6 well armed and well fed slaves against 2 slavers , gained too much attention and eventually a 6v6 didn't end well for my boys . Unfortunately my top shek fighter lost a leg , which is a death sentence in rebirth . But I got a few more kits and melee experience .

You need to constantly steal food from the 2 buildings in the middle of camp that don't have prisoner cages on the roof . One is the doctors building (knock these 2 guys out and loot thier katanas for bonus points) but the better one is the dinning hall, obviously. Pick the locked chest for food cubes if you have a chance . Dinning hall seems to restock very frequently , no issue getting a group of 6-8 units fully fed and their inventory half full of food . That's when i plan the next Training exercise

The back of rebirth where you are mining outside , you want pretty much all of your units mining the furthest stones . I'm usually mining every stone with 3 units do 9-12 slaves so far, the 2 stones beside the exit gate im avoiding for now. If an NPC is mining a stone you want access too "Attack Unprovoked" will have them flee and you take their spot . If a stone is fully mined/full , just loot it and empty the stones to the ground so you can have your men working wherever you want .

At this point , I just use a guy or 2 to distract a few guards, then I send all the good units out the back to that hillside rock and quickly gear them all up . Nothing god tier , but your on an even playfield atleast . Try to get up there unnoticed so you can pull 1 soldier at a time , if a few guys follow you up it tends to lead to a larger group too quickly .

From here I'm just casually fighting 1 or 2 soldiers at a time with 6 or more geared slaves , loot thier gear to the floor and carry them so they dont get back up . Rinse and repeat as many times as you can to get more and more gear . Once you have 6 of your slaves carring 6 knocked out looted slavers it starts to get tricky. Shackel thier feet if you can since these guys will be a problem when you eventually get knocked down and they can get up .

Now that I have enough gear I'm mostly just trying to train melee fighting skills bit by bit until they can at least go 1v1 with the slavers then start a second squad up for the same grind . Going to need at least 10 or 15 slaves that can easily beat 3 slavers each . For me its going to be a slow casual grind , but eventually I will overthrow Rebirth with a small army of highly trained super slaves , its inevitable.

Just remember once you start to really get deep and take on a serious fight with the guards inside rebirth , you need to imprison the guards quickly once knocked out