Probably not Steve. Hopefully more knowledgeable people will help here but an interesting pic from a uniform point of view. 1930's pre Third Reich Germans, one with a M18 cut out helmet. A forgotten period as far as figures go I think.
I don't think it would be that bad an idea. Horses used to be trainee to not react to gunfire. It looks a bit circus like, but I think both the men and their beasts where trained enough to pull it of. And the Mauser, even if it's quite powerful, is pleasant enough to shoot standing up.