Li Shenron
Legend
When a paladin is mounted on a large creature (warhorse, elk, who really cares), where does their Aura originate from?
As I understand mounted combat, you are occupying the space of your mount, and for a lot of basic stuff with a large mount, you are considered to just be in that large area somewhere. However, extending the paladin's aura while ok in the short term, might lead to problems if the paladin is mounted on huge creature, such as a dragon or something.
However, just picking a hex could lead to the paladin's mount taking up more of the aura than strictly necessary and weakening the aura by allowing fewer opportunities for other players to benefit.
I think the aura's range is simply counted from the original Paladin's medium-sized occupied space.
If you use squares/hexes you probably just pick one of them and count from that. I don't use them, so I just measure the distance with a ruler.
A gigantic mount can possibly cover your whole aura, so what? You have a gigantic mount!! Your friends might actually want to jump on it too sometimes, in which case they will probably benefit again from your aura.