Holy necrobump, batman!
Alternatively, since FFXIV will have male mithra and female galka, perhaps you can open those race options for FFXI, and then give everyone a one time appearance change.
No. First, FFXIV won't have male mithras and female Galkas, because the game doesn't have either of those races, as it is not FFXI-2.

FFXI has explicit lore reasons why female galka don't exist at all (technically, they arent male or female, as they are asexual), and why male mithra are not playable. FFXIV had no such lore reasons, and in fact a female Roegadyn was the leader of one of the Grand Companies. To add females to an asexual race doesn't even make sense, and would be a massive retcon of the game's lore.