Heather Gerken, Wade Gibson, and Webb Lyons have written this WaPo oped.  A snippet:

Unless and until Congress and the Supreme Court fundamentally change the regulatory environment, proposals like the IRS’s won’t stop the flow of money; they’ll just reroute it. The story of 2016 and 2020 will be the same as in 2012, except with a different set of organizations serving donors’ needs. Given the hydraulics of campaign finance reform, we should focus not on stemming the flow of money but rather on directing it toward greater transparency.

Here is one simple proposal for doing so: Congress should require that any advertisement funded directly or indirectly by a group that does not disclose its donors acknowledge that fact. This “nondisclosure disclosure” would be simple and truthful: “This ad was paid for by ‘X,’ which does not disclose the identity of its donors.” That could help voters figure out how much trust to put in the ad.