I don't know if they come in much thinner shims, but you should get more of an assortment. Like I mentioned earlier, I used 2 shims that totaled .028". My thinnest of shims mic'd out to .007" or so. Spread out your shims and organize them into piles according to thickness. Stack shims together to get roughly .030". Go from there.
OR, find a local R&P shop and ask for some shims, they should only be a few bucks if even free. They normally give you a bazillion in each kit. They probably have stacks upon stacks.
But at any rate, I've been pleased at the assortment my Yukon kit gave me.