I used fusible for some large baby quilts and I loved it. I did use pins about a foot apart. I don't think I needed them but I wanted to know if the top or bottom was shifting any and the pins would be the way to know. I quilted them within a week of when I put it together so I don't know how long it will stay ready to sew.
You might just try using it and if you aren't happy, fold it back up and use for other projects.