What to do about corrupt special interest influence in government

I posted this as a comment on Facebook (slightly edited), but it represents my long-held opinion. I think this problem is so pervasive, and so destructive, that only a "root and branch" approach has any possibility of working:

I concluded long ago that not only do we need public financing of (short) political campaigns, but it should be illegal to take any good or service from anyone for any reason while campaigning or in public office, with severe penalties. If you can't live with that, don't run for office. (OK, there would have to be exceptions for presents from immediate family members... but that's it). And any quid pro quo that shows up after the official leaves office (such as job offers from regulated industries, lobbying jobs, etc.), also should be illegal. Officials should learn to err on the side of caution, lest they spend a few years eating prison fare. Unenforceable? I think not... it's no worse than, in fact in many ways similar to, laws against insider trading, which don't work perfectly but which do work to some degree to "keep 'em honest."