I don't know if I support this... I would not like to see a donkey invasion.
If it is not possible to make the horse model smaller it should be considered a big donkey. Thus the health should not be set to 50. That is just ridiculous if it is the same size as all other horses.
Just make it slower and less manuverable.
The price should be higher than sumpter horse to prevent every foot soldier to get one (with their spare 1 skillpoint put into riding).
Maybe something like this for the donkey:
Donkey 7500
hit points 80
body armor 10
requirement 1
horse speed 30
horse maneuver 35
horse charge 4
These are the stats of a sumpter horse:
Sumpter Horse 4789
hit points 90
body armor 10
requirement 2
horse speed 35
horse maneuver 37
horse charge 9
... And don't forget the mules and zebroids!
![Smile :)](https://forum.c-rpg.net/Smileys/default/icon_smile.gif)
Camels are also an option but then the 3D model needs to be changed or it will just look stupid.