How do you circumvent donation limits and exploit a matching donation program to boot? Ask the real estate developers who "launder" contributions to the Los Angeles mayor and city council as explored this report by the local NBC affiliate (transcript and video available).
By funneling money through third-party cut-outs, big donors are circumventing imposed donation limits to their favored candidates -- to the tune of $180,000. It's difficult to punish, because it's hard to detect and once investigators gather enough evidence to make their case years have usually passed, the election is over, and the money is long spent. Plus (and this is the same enforcement issue we run into with donation bundlers who are also criminals) can you really prove that candidates knew about the laundered donations when they accepted them?
This is the trouble with trying to address campaign finance concerns on the supply side. So long as big money is needed to run a campaign, nefarious donors will find a way to get it through. The answer is to address it on the demand side -- give candidates an alternate way to finance their campaigns that doesn't involve depending on a small, wealthy group of people, but rather on general public support: full public financing.