addressing nocturnal arousal discomfort with a cage

I’ve recently started exploring chastity play. I’m using a generic CB6000 with a 3.25” opening, alternating between its 1.75 and 2-inch rings. It’s comfortable enough for daytime wear, but at night, the pain from nocturnal erections is so intense that it wakes me up within a couple of hours, often forcing me to remove the whole device just to fall asleep.

My question: I suspect part of the issue might be due to using a knock-off model, but could there also be a sizing problem contributing to this pain? Additionally, is there any adjustment or fix for when an erection causes the cage to slide forward and leaves me hard with only about an inch left inside it? If I can get erect up to 60-70% of my length while keeping that last bit soft behind the cage, it feels like the cage isn’t doing its job properly.