I made a DIY quilt, and have a hammock gear incubator. Neither have a bottom "opening". I find its really easy to push the UQ to one side, get in, and let the quilt snap back into place. I have seen instructions for an underquilt with a bottom loading "door", basically you add Velcro that the Hennessy Velcro attaches to, and when you close the flap, the UQ clamps shut too.