It's a really pity there aren't more rack bags designed for folding bikes. You've got acre of room above the rear wheel, so there is really no need to have something hanging over the wheels or sticking out sideways. A tall bag that would be a hazard on a road bike, and raise the centre of gravity, would actually lower the centre of gravity on a folder.
Still, the paddywagon looks ok to me, barring heel strike.
(this is what I mean, using up that negative space that is on all small wheeled folders)