but with my old injury (boxers fracture on my ring finger) will I be able to condition to be able to go bare knuckle?
Yes. Because it's a gradual and gentle conditioning where you aren't punishing your knuckle. You just want a tiny bit of discomfort like the feeling you get from hitting something and you know that if you hit harder it's going to hurt or bruise. Any bruising that occurs should happen after 10 strikes or more then you stop. If you bruise your knuckles within 5 or 6 strikes with the same hand then you are hitting too hard. Think of it like knocking on a wooden door of a house there's only so many knocks you can do before your knuckle gets tender.
As for your old injury you can avoid hitting that knuckle too often by focusing the force of your punch on the first e knuckles or just on the second knuckle. For me my first 2 knuckles get more conditioning than the ring finger. The first 2 knuckles are the common knuckles that practitioners hit with. Because of the system I train in. The other knuckles I hit with are the first 3 knuckles that you use to knock on a wooden door. My fingers still look normal and my joints aren't deformed, nor do I have joint pain.
I do these exercises as well. They are simple to do but you'll definitely feel it when you do it correctly.
Tiger Claw Grabbing
Flying wing
Grabbing Air Tiger Claw
Windless
The tension grabs are really good for strengthening the tendons, ligaments, and muscles.
Have you seen students with similar hand injuries be able to recondition their hand to handle the stress. The last thing I want to do is damage my hand more, due to not protecting this old injury.
This depends on how bad your injury is. I have seen students with hand injuries and knuckle injuries have successful recondition, but it was mainly because they learned how to target the correct knuckles which takes the 3rd knuckle (ringer finger) out of the equation as it's no longer used for striking, which in turn reduces risk of injuring it again. That 3rd knuckle will still hit but it won't hit with any significant impact in comparison to what the other 2 knuckles are getting. You should be ok as long as your injury doesn't require surgery. If you condition your hand and focus your power on those 1st two knuckles then that old injury shouldn't be getting a lot of action.
It doesn't take super punches to hurt someone once you get the technique, conditioning, and power connection with your punches
Here's a video for you.
I'm the guy taking the punishment. I'll never do this again because it causes more damage than what it looks like and feels at first. If I wanted to put someone down, then I would use the technique shown in that video but I would do it hard as if I was trying to punch his soul.