Have you checked out those nice packs that many of us who hunt with bow,use,lumbarpacks that have harness too.
something like these:
http://www.ammoland.com/wp-content/uploads/2009/05/hunter-lumbar-pack-l-l-bean.jpg
http://www.thewoolking.com/Products/LumbarPack_S.jpg
http://images.cabelas.com/is/image/cabelas/s7_517938_imageset_01?$main-Large$
something like these:
http://www.ammoland.com/wp-content/uploads/2009/05/hunter-lumbar-pack-l-l-bean.jpg
http://www.thewoolking.com/Products/LumbarPack_S.jpg
http://images.cabelas.com/is/image/cabelas/s7_517938_imageset_01?$main-Large$