long-term couple looking for new wife

My husband and I have been in a stable and exclusive relationship for almost 21 years now. For the last five years, we have discussed adding another wife. Our kids are almost ready to go to college now and I believe mature enough to understand. We always wanted to have a lot of children, but that was not in the cards for me. My body let me down. My husband loves kids and loves the company of women. He would never cheat on me or anyone he made a commitment to. A polygamist relationship makes sense to us. Even though I really love my husband, I wouldn't mind another wife. Sometimes I like to just be by myself. (I'm currently writing a book, which takes quiet "me" time.) At those times my husband feels neglected which isn't what I intend. My husband grew up with a lot of people in a small house and doesn't like to be alone. I also would enjoy having someone that I could bond with and share the household with. We don't go out a lot, when we do we like to go to concerts or dine out. We are not big partiers and I am not looking for a bisexual woman. We consider ourselves to be soulmates and are hoping to find someone else to fit into our life. We are new to this and willing to learn. We believe that we have a lot of love to share and go around.