There are some photos showing them training in SA in shirtsleeve order so I would guess as the war continued they got a bit more savvy. If I remember they were there pretty much in at the start in 1899 coming from Aldershot ( rather than Australia as they had been in training in GB) and they were short of most things including horses. They wore helmets in Dec 1899 (under duress I think) for one reason - several accounts of them being shot at by British troops mistaking them for Boers. This suggests maybe the red plastrons were not being worn or they could be saving them for best rolled up in the greatcoat as a replacement would be unlikely. British troops gradually learnt how not to shoot everybody in a slouch hat as volunteer and colonial/loyal units built up.
I am looking forward to these figures.