Searched but didn't find a suggestion for a removable trunk lid. This would allow large objects in "Hauling" mode. Bicycle(s), electric lawnmower are some items I'd use it for. Add Weathertech rubber matt, D rings for ratchet straps that secure a load & something like a durable rubber 'pool noodle' to protect car body edge.
Other reasons for removable trunk lid? Tailgating, camping, emergency response. Remove gear from car & use it as bed. Attach tent to opening. If lid has PV, aim at best angle for sunshine & run cable to car for best charging.
I'd be OK if speed had to be limited to prevent highway use, ie 45MPH. I don't see why but for liability. The car would know when lid is removed. Just an idea.