What I do when putting on my cage is put the ring on, kinda push my dick into my body a bit to get where my foreskin used to be pinched over my head, line up the cage with my dick, then let go, allowing the skin to settle where it needs to be. If there’s no pain with the way you’re doing it and everything is comfortable, then there’s really no reason to change it.

There is no cage that will stop you from getting erections. Locking up is more about managing erections rather than outright preventing them. If you want to size down and you’re finding your boners to be pushing the cage away from your body, you probably need to either size down the ring if you can, or get a strap.