My hubby complained that our king size quilt with 1 layer of Hobbs Heirloom 80/20 and regular cotton front & back isn't heavy enough so I made him his own personal throw size quilt with old denim for the backing and his old work shirts for the front--faux cathedral windows style. He uses it every night.
Yes, you can quilt or tie multiple layers of batting or fleece. You can also an acrylic blanket or old quilt for batting in a new quilt to make a heavy quilt.