Yeah, a queen will do but a king is best.
Engage in lots of PDA and enjoy any scandalized looks you receive.
If you haven't already, as just a general peice of advice for three person relationships, read this: http://www.morethantwo.com/coupledating.html
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.