If you form a corporation, then you can write them off as a cost of doing business. Same thing with hosting, domain purchases, etc.
If you are audited by the IRS, that will be the least of your problems. There are legitimate uses for proxies in any number of business environments - there isn't any need to lie about it unless you are using them to spam whitehouse.gov or pop firewalls at the DoD or something.
Why are you worried about this, it isn't even tax season?
I'm not a tax professional (however I AM married to one, lol!). Wouldn't the cost of proxies be just like any other business expense? I don't pay for them personally, but if I did, I'm pretty sure I would deduct their cost from my income.