I say don't push her on this. You've made your feelings and desires clear to her. She can let you know if and when she wants to go there with you. I can't say whether you will destroy your marriage with your proposed activity. However, I do think you are playing with fire.
Sexual energy is very potent energy.
It is part of what keeps marriages vital and it can wreck marriages too if misapplied. You are just talking when you say that you won't form attachments to the other women you sleep with. I don't believe that for a minute. You will, if not the first time, then the second or third or forth time. Anne has been helping the confused and heartbroken for over 10 years.