I first put this comment on your personal ad, but it's more appropriate here.
You wouldn't be able to legally marry this ideal woman, so she could never be equal, in the eyes of society or the law.
Would you 2 and this woman be completely "out" as an equal triad socially? Or would she need to be a dirty little secret to family, job bosses and colleagues? What about PDAs as a threesome? What about dating/fucking each of you separately, as well as sharing 3some time, in or out of bed?
You seem like nice people, but I wonder if you understand why you're having such a hard time finding your unicorn.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
There's no lying in polyamory!
I'm a 58 year old woman with 2 partners:
miss pixi, my live-in gf, 36 (together since Jan '09)
Ginger, bf, 61, married, lives nearby (together since Jan '12)