With its adjustable shelves, the IKEA Mandal headboard is already fairly adaptable, but have you thought of using it in ways other than a headboard? These folks did; perhaps it will inspire you to look at the Mandal with new eyes of possibility.
Ikea mudroom hack: Pax closets, ekby shelf and corbels, gerton desk top, kallax bench seat, and pjas baskets. I wonder if this will fit in the hallway or if it would take away from the entrance? Or in the spare room?