We need to find a way to develop a female chastity system that does away with the awkwardness of the back opening, while still providing quality protection from stimulation for the wearer.
There's the possibility for the back opening to be unhygienic, and more importantly, some of them look like it would cause discomfort for the man penetrating her. Like the one in the picture in >>167 is. Look at those metal sides on the inside of the back opening. Those look like they could scrape the sides of your man's cock real bad while he's fucking you. When he's fucking you, you want him to be free to think about how you haven't cum in three years, but he and his vixen do every night, not 'I better be careful to enter perfectly straight, or I might get a rash on my cock'.
There's the piercings, but they have a couple downsides. First, he may simply not want to put holes in your labia, which is perfectly reasonable. But also, they tend to not offer proper clit protection in the way a proper belt would, and even ones that do cover the clit will be vulnerable to vibrations. It's all well and good to close your pussy for business, but if you can still get off with a vibrator on your clit, then the chastity system is woefully incomplete.
Science must find a way.