Personally, I'm wary of any sort of goals or intended destinations in poly. It seems like it's very hard for people to shift once they have their hearts set on something. When you're dealing with the complicated interactions that happen between multiple people, the ability to deal with fluidity seems to almost always be necessary, and pre-determined ideal outcomes don't seem to lend themselves to that.
For instance, in your situation, you're acknowledging that you can't know how things will be without input from a future partner. Very true! But, ultimately, you're still seeking someone who can be with both you and Pidge -- you speak of one person, not of one or more, and you speak of both you and she being involved with that person, so I think it's fair to say that's what you're after? -- and with that comes all the much-written-of pitfalls of unicorn hunting.
To name the most obvious one, let's say you two meet a lovely man who you both like! Step one of the five year plan complete! And he likes both of you! But then, over the course of months of dating, it turns out he clicks with Pidge very strongly... in fact, it's love... but he no longer wants to put his strong arms around you. Will that be ok for you? Or, in the same situation but reversed, will it be ok for Pidge? Or will the disappointment of "failing" to reach your desired destination be a stumbling block to moving forward?
The major players. Me, 30ish bi female. Gia, girlfriend of 4+ years. Clay, boyfriend/dom. Davis, ex/friend/"it's complicated." Eddie, roommate & fwb.
The supporting cast. Eric, Gia's husband. Bee, Gia and Eric's toddler. Dexter, Gia's lover. Helen, Eric's lover. Izzy and Nikki, Clay's partners. Liam, Eddie's husband.