So I'm a pretty large guy (stomach not dick) and I've had issues in the past with my dick slipping out of a cb6000s because of this. Is there anything else I can try in order to stop my dick from wanting to slip out, or another cage?
You need a PA-piercing - then all of your problems are away.
In my experience anti-pullout devices help some but I believe most people can pull the chastity device away from their body enough that they can pull their cock out. The only sure way that I've found to prevent this is to use a true chastity belt.