Ha, this is so funny as we always had the exact same conversation and issues. We started by trying to swap and we did a bunch of hunting for couples and only ended up doing it once after a couple meets and one always taking one for the team conversation. And we decided to open up for exact same reasons!
So we had rules too and just so you know the above and this open period was all in first 6 months and happened yrs ago so in the end we are together and happy, something you need to realize reading what I will tell you.
Our rules were, pics nice but not mandatory, some men, especially married ones dont like that nor want to know about you, we did same always tell details, always know where the other one is for safety but in the moment was ok as long as informed later, no dating, sex only. Condoms, no one in circle, no singles.......Well over time she broke rules too, mostly about not knowing everything, which I found to be hot later and she did sleep with 1 single guy but she did ask permission and so did he. She would give me details but she admitted it was uncomfortable and later she agreed to let the guy tell me if I wanted details.
I found best way to keep her steadfast to the rules was my successes, she got jealous easily so I upped my game, did whatever she did that I didnt like and it got fixed pretty fast.