If you have space on the garage wall, build a flat shelf which is deep enough to contain the trunk's entire length and width (thus protecting it).
Drill some 2x2x16" (rough) pieces of 1/8" aluminum angle stock so that the I/S' trunk mounting brackets may be fastened to them, and so that the angles can be bolted to the shelf. Measure and drill the shelf; attach angles.
Place trunk on the angles. Front two holes can be retained by pins of your choosing, and I'd use bolts, nuts and washers to secure the rear mount points.
Problem solved. Problem staying solved.
