Novices and newbies discussion

Hi there, I’m considering purchasing the rigid chastity Model 5. My size is bigger than average but not massive like a porn star.

1. *Base ring…Should it fit snugly or be as wide as possible for extended wear? It seems if you can slide your balls through the opening, they might slip out? It’s tricky to tell what feels comfortable versus secure?
2. I understand how to measure cage length basics. But does being a bit tight or loose matter much? No prince Albert piercing here. Like when trying to grow…the tip of the cage? I once had a jailbird device with a sharp weld at the top, and when fully erect it would sometimes scratch me… so I replaced it.
3. Interior diameter: The website suggests using girth while erect…But my shaft curves upward, whereas the cage curves downward. Since the recommended length is shorter for that curve, I wonder if I can ever get completely hard inside this cage?
4. Interior diameter: My flaccid penis fits snugly in a 4-inch model (skin tight). It didn’t let much air circulate…which led to chafing and constant moisture… I’m thinking of getting one large enough for airflow when soft, but just slightly under my full erection size. Too much room might allow pulling out? Eager to find a high-quality device. Also looked at the Pet Trap from Mature Metal. Any other custom devices worth considering?