People who play as custom races (including myself) usually face an issue when the game does not recognize the character's race properly.
Gameplay-wise, most of this is fixed with the http://www.nexusmods.com/skyrim/mods/19 and http://www.nexusmods.com/skyrim/mods/24168 mod.
However this is only a workaround, and there are some dialogues or interesting reactions available depending on the character's race.
For example, the mod http://www.nexusmods.com/skyrim/mods/50802 allows you to either modify ALL the vanilla Khajiits' heads, or add a standalone race for player only.
If you choose the latter, while the character looks like a Khajiit, the NPC interaction is bleak since the game treats it as a separate race entirely.
Would it be possible to use, say SKSE, to trick the game into thinking that the player character is some other race?