i spray baste mine. i use a folding table from JoAnn's to lay them out on. then i lift the top section and spray and lay it back down, smooth and move to other side. lift up, spray and lay down and smooth. then to the sides and do the same. then turn over and smooth the backing again and start there doing the same, lift, spray, smooth, move on.
that takes long enough to make my back hurt but it still better than ironing fusible batting (which i also use) or pin basting or thread basting.