So I want my new Khajiit, Ra'Darrenrij, to primarily equip light armor, but I will boost his heavy armor skill to 30 for fists of steel. A couple of questions though, does the Fists of Steel perk work with Light Armor, and if so what are the most powerful Light Armor gauntlets? It seems from a brief glance at the wiki that the Ancient Shrouded Gauntlets appear to be with a base Armor rating of 15, but I cannot enchant those with the Fortify Unarmed enchant...

Fist of steel needs heavy armor gauntlets to work.

-Really- what you should do is just use enchanting (and maybe the restoration loop if you want a full fledged unarmed power) to enchant some light armor gloves.
The reason is that fists of steel will require you to wear heavy armor gauntlets- which will make all your "matched set" perks not function. And the boost from fists of steel is capped at something like 14 damage (whatever the base value of daedric gauntlets are). So you are better served with enchanting and a loop.

it's 18 damage, and it's worth it considering that without it the max damage a khajiit can achieve unarmed is only 50, as opposed to 68.

These numbers aren't a boundary (because of loops or necrovamp effects), 18 damage (at the cost of 2 perks, and a negating of your match set perks) is 18 and doesn't improve.

If you don't enchant, it is worth the fists of steal perk. If you do enchant, don't bother to take the perk.

And you don't have to be a khajiit if you do the restoration glitch.

Just do it enough to make your unarmed to a reasonable amount of damage.

I like my Khajiit, I had one before and his unarmed was still functioning okay well into the high level 30's. I wanted to make this one a bit shadier of a guy though.

THAT is a bummer. I guess I'll stop wearing the Imperial Armor then, and switch to Alchemy as my main source of healing/invisibility. I haven't yet gotten a straight answer on how high your alchemy has to be/how many ranks of Alchemist to take before the restoration glitch becomes viable. Seems like it requires well over 30 though, otherwise I just guzzle potions like a drunk at a wine tasting.

To help you out, just make sure your enchanting is at level 100, and have some perks into it (I always put seven up the middle line). Then make your five pieces of alchemy gear (falmor helmet and circlet for your head) and it shouldn't take you that long to reach ridiculous percentages using the restoration glitch.

Well, I'm not going for ridiculous, just "on par with an actual weapon."

it's not like it requires any sort of glitching, believe it or not 68 damage is perfectly viable for unarmed damage at end-game.