Looks good. It seems to me, Palissa, you like challenges. Reins - good idea!
Can you skin the saddle in a smaller version? That red leather should be at his thigh.
Stirrups seems really hard. I would draw them to the rider's model but good question with or without thongs. Maybe it doesnt worth the time.

If Pinarius made steppen horses I suggest to use them. Magyars had such horses in these ages (and all the nomads in the game).