Haramaki is a light armor that gives +1 ac at 0 % casting failure chance. Same thing works with Ceremonial silk armor, but it's heavier and costs more. -- now if you combine that with an armored kilt, then the set counts as medium armor, thus it may or may not slow you down. After spending 21 gp (or 50 gp for silk), you now have +2 AC with up to +6 dex bonus, and 0 % spell failure and 0 Armor penalty - so even if you're not proficient with any armors, this seems to works, RAW that is. Does it?
Bonus, could this be worn at the same time as or integrated with mock armor?