I haven't seen one so far, so I'm going to go ahead and say how I think it could work, in a way that could be easy and vanilla-suitable.
Make three new races, a Half-Dunmer, Half-Altmer, and Half-Bosmer. For the sake of suitable skin tones and character heights, you could simply put Dunmer ears on an Imperial, Altmer ears on a Breton, and Bosmer ears on a Red Guard. If one was capable of making them more realistic without sacrificing functionality (like face and body tone differences), ie more modded, that would be great. (And hey, while we're at it, an Orc-Nord would also make a fine Half-Orc, but that's not my main goal here.)
When it comes to Skills and Specials, I would like them to remain mostly elven, because unless we make specific Breton-Bosmers etc, we don't really know which human traits to give them, and it could mess with ones ability to role play them. I certainly don't want to play a Half-Bosmer with Nordic frost resistance when she's meant to be Imperial. So instead we create the impression of a Half Elf, neutral of human race, with altered skills, the greater powers of their elven side, and more humanised stats - such as more endurance and less agility, things like that.
Half-Dunmer: Takes after the Dunmer's magical warfare, with a slightly berserker bent.
Skills: Athletics, Blade, Block, Blunt, Conjuration, Destruction, Light Armour, Mysticism.
Half-Altmer: With the magical power and frailty of their elven parent, a Half-Altmer tends to compensate with more sources of endurance, both magical and mundane.
Skills: Alteration, Blade, Destruction, Illusion, Heavy Armour, Restoration, Speechcraft.
Half-Bosmer: They cope almost easier with their strange ancestry, since they can seclude themselves as rangers, and so easily maintain the Bosmer's skill as a scout.
Skills: Athletics, Acrobatics, Alchemy, Hand to Hand, Light Armour, Marksman, Sneak.
Edit: And for the prison scene, I thought it would be terribly convenient and amusing to have that guy mistake the PC for their elven race, through the gloom of the prison of course.. That way we can avoid breaking character by adding voiceless text or skipping it entirely.
So that's the gist of what I'd like to see. If anyone would like to make it, the rest could be discussed! I do hope someone might be interested.
<3