How do I lower my tax exposure?

Too late now. You need to think about tax implications before you start trading if that's something you're going to try and optimize for. At the very least understand the wash sale rules so you know how to avoid taking losses that won't reduce your net profits. If you've been doing this in a personal brokerage I think that ship has sailed already and you're going to owe whatever you're going to owe. I feel the pain man, short-term cap gains suck and it's been a great start to the year already...

Well first, you should come to grips with that fact that you are being an absolute POS for wanting to skirt your duty as American citizen.  It's not enough you have been given the ability to generate wealth without doing a thing, but you have to take it a step further, and not contribute to the society that gave you such a privilege.  It's honestly sickening to me, do you think an oil driller, coal miner, or garbage man gets to avoid his tax bill?  Additionally, trading is one of the slimiest ways to make money.  Unlike it's respectable cousin, investing, which allows businesses to grow, and jobs to be created, you just come along and want to extract a quick buck at the expense of someone else, and be on your way.  

Once you've realized what type of human being you are, I suggest you talk to a CPA / tax attorney, especially if you have been dealing with derivative securities, as the tax implications, and planning strategies can be very complicated, and failure to comply can mean fines and interest.  As another poster said, it is generally best to think about these things ahead of time, although in general, unless you are dealing with a huge amount of money, or are retired and need income now, my opinion is that taxes should not be a key driver in your decision making.  

Edit:  Not sure why the MS being thrown my way,  I think this is entirely reasonable advice for OP, wtf?

Edit 2:  Again, no one has pointed out a problem with the tax advice.  Taxes around trading can be extremely complex, so what's wrong with speaking to a licensed professional on the subject?