I quilt without any hoop or frame at all. Although I've never done a king size quilt I have done up to Queen with excellent results. I just baste well, pins or thread, and smooth as I go beginning in the center of the quilt. I use a sharp needle and a running stitch. I average about 8 stitchs an inch which is OK with me. As Mermaid said it is nice in the winter time to have that quilt draped over my body as I work!!
PS: I don't have any problem keeping the quilt square if it is squared before I begin.