Hmmmm, so it sounds like I do have to worry about the back seams fraying really bad. I'm not sure what to do then. There's a fabric in it that I think will bleed even though I prewashed everything. I dampened a block to remove some freezer paper (put it under a hot iron right after to dry it quickly) and just in that little bit of time a black fabric bled on to a white fabric. I have some Synthrapol to put in with it, but I know it needs to be put in the dryer right away to avoid sitting around damp. So that takes blocking the quilt out of the scenario. There is some water soluble fusible in some of the applique though so I have to get it completely wet.
I guess I'm going to just have to wash it after it's quilted, dry it in the dryer and just hope it comes out as flat as possible. Will prewashing my batting help keep the scrunch down? I've never prewashed batting so I don't know how to do that either. :P