What I meant by playing it cool was keeping your expectations low.
Quote: It was only when I got more assertive that progress was made, not by hanging back.
I'd still do this... be assertive about you. Be fun, enjoy your time with her, but a little bit indifferent to the outcome. You don't need her, but would prefer her to be in your life.
Quote: But would have to think there is also something to be said for finding a way to let her know the door is open without it being a sign of weakness.
If she's curious about the possibility of getting back together you'll know. As long as you have never told her that it isn't possible to get back together, then I'm sure she's aware that there is a possibility. In this case you want her to come to you. Leaving the bedroom door open might be good, but you'll need to create attraction during the stay.
Have you ever read frank_d's thread? I can send you some of the stuff he gave me. Shoot me an email.
Me: 45 W43 S7, Foster S9 (Planning to adopt post divorce) D mentioned Feb 2015, Wife served 3/24/2015. She moved out 4/15/2015.