the sorrounding area. It is unfortunate that nissan welded a section of the tray to the shock tower. Considering the condition of the that tray I would remove it, clean well around the area, especially below. You definitelt don't want a hole to develop in the shock tower. Then, mount the battery in the spare tire well and run a Conti Compfort Kit. My new Hyundai has that, no spare. Optima makes a thin 1/2 cell (6VDC) that is only 4 inches in thickness. Use two on thier sides in series. You will need to build a suitable support for the batteries as well as the cardboard floor suppport that depends on the spare. The + cable can be passed through a plugged hole already in the tub. The - can be attached to the spare suport threads.