I use flannel for batting if I'm going to be doing heavy beading. I baste the top to the flannel, do the beading, and then add a back and bind it. So far my heavily beaded pieces have been quite small and I haven't needed to quilt them as the beading held it together well enough. When I made the quilt in the avatar, which is 39" square, the beading was a small part of it, so I used a standard thin poly batting, quilted, and then added the beading last.