The only way to get rid of lobbyists is to make donations from anyone who does not have a constitutional right to vote illegal. This takes out churches (but not their members), unions (but not their members), lobby organizations and PACs (but not their members), etc. I also would limit donations to those in the actual constituency of the election. Now, how to enforce that is a different, and potentially prohibitive, issue.
Great idea but with the attendent problems you mention. I would rather deal with those problems, though, than the unions and the Soroses.