[DF] DF Equite

[Humabout]

If you're dead set on a new template, you could probably do well to mine the mounted styles in Martial Arts for some basic ideas:

Armatura Equestris (p. MA150)
Bajutsu (p. MA151)
Furusiyya (p. M159)
Knightly Mounted Combat (p. MA175)

From that, I'd gather a list of fitting traits and skills. You might also consider adding Animal Empathy [5] or potentially Speak with Animals (Specialized, One Family, -60%) [10]. Good with (Mount Type) [1], Higher Purpose (+1 to rolls involving riding or being mounted) [5], etc.

Power-Ups could include traits constructed from various riding-related techniques.