I ordered one these but decided that it was not long enough (i.e., at 30" long, it did not protect the bumper top across the full width of the hatch opening). A longer and wider 37" model is available and would probably work well but no one would ship it to Honolulu!
Instead, I ordered this bumper top protector
. At 41" long, it protects the entire width of the hatch opening. It is also the perfect width in that it covers the entire area of the top of the bumper front to back. It looks like it could be a standard feature of an i3.
The only problem was that the final layer of the included double-stick tape pulled a layer off the cardboard center tube of the tape roll so would not stick to the bumper top. There was just enough tape to attach the entire perimeter of the rubber protector to the bumper top but not enough to attach the center area of the protector to the bumper top. Time will tell whether more tape might be needed, but I could purchase more locally, if necessary.