I'm making a Grizz inspired, lightweight, convertible bridge hammock. I plan on ordering a couple of the JRB quilts, one to use underneath, one on top. I need to sew some button holes along the channel where the suspension rope will go so that I can attach shock cord for attachment of the underquilt. Does anyone know where the tabs are located on the JRB quilts (how many inches from the ends or from the center)?