In any case, with the hub spinning freely, I couldn't remove the nuts. I needed a way to lock the hub in place. I took some rope and tied it to the body up around the front. I took the other end of the rope and looped it around one of the nuts, like so.
* - With the visual acuity that comes of hindsight, the transmission mustn't have been fully engage, otherwise the rear wheels wouldn't have moved. I think. Another thing to try tonight.