Vox: Okay. I understand your question. You are in a committed relationship. You need someone to surrogate for you. Normal surrogate situation except that you want total control over what the surrogate is doing with and to her body while she is carrying your child.
I have always thought the idea of carrying a child for someone else would be a very difficult yet rewarding experience. Given that I have thoroughly checked out the potential parents and get the feeling that they have a stable lasting relationship. Would I sub to them? No. Would I allow them to have a say in what I put into my body while I am carrying their child? Probably. Though I would not be willing to move into their home just so they could monitor me for nine months. I would want to keep my own space and my own life as close to normal as possible.
I can't answer honestly about being in the exact situation you describe because I am not someone who could sub to a Dom in a relationship with someone else. To do this for a friend though? Yes. I would do this for a friend. I would expect her to be involved as much as possible.