I'd try putting the bottom bumpers under the plate so that the top bumpers sit lower on the glass. Don't know if that'll work but IMO the closer you can get to the edge of the glass with the top the better off you'll be. Another option would be to put the lower bumpers above the plate and pick up the glass near the top. That would also help you with the top straps, which then wouldn't be sitting on that spoiler lip thing.