Assalamu alaikum, sisters - need advice on piercings

Salam everyone. I'm a Muslim sister wondering about getting a piercing on my lower back. The only people who would ever see it would be other women (like if changing around them) and my future husband insha'Allah. I've read some opinions that say it's okay if it's not publicly visible, but I wanted to ask the community for clearer guidance. Also, I forgot to ask earlier - what about a collarbone piercing? Is that permissible? JazakAllah khair for your help!