I haven't used the newer cotton batts but the old Mountain Mist required very close quilting. Now-a-days when I'm doing a tied project I have used the good parts of old 100% cotton sheets for a very flat look. I've gone the old-time route and used an unattractive comforter as filler, though I'm sure you wouldn't want to do that for a baby--too puffy. For a baby you might cut a new 100% cotton flannel sheet into layers and use that for your filling. Then you could enjoy the tying process without worry about spacing. Do be sure that the ties are secure enough and/or cut short enough that baby cannot 'mouth' them or tangle little fingers.