What if you start a new Amazon EC2 spot instance (netting you a new IP address), start up Chromium in headless mode (say, using Xvfb), navigate to the website of choice, use mouse automation to start clicking around, click the ad, spend 5 minutes clicking around in a semi-choreographed pattern on the advertisee's website, and then shut down the instance -- only to repeat?
Moreover, Amazon is always buying new IP subnets.