As it stands, none of the Gunslinger Ways really support riding a mount, which is a big part of some people's gunslinger fantasies (I know the gunslinger I'll be GMing for tonight will be using Cavalier archetype). Drifter and Pistolero both have movement as part of their first level feature, which can't be used on a mount. And snipers require stealth, which while technically possible on a mount doesn't fit the fantasy.
I don't expect gunslinger to have any way to innately give someone a mount, we have archetypes for that, but a Way that works with it would be appreciated.