There are many sides to this.
Defining immigration law advice would be a good start. There has been a lot of discussion in the media and elsewhere about ghost agents, but the term “immigration law advice” has never been really defined in detail. That's really important so that we're all on the same page and all speak from the same foundation. That would be a good start.
Second would be changing proposed section 91 to ensure that nobody can assist a ghost agent, not somebody outside the government, and not somebody inside the government.
Those two things would go a long way in moving forward, as would making it an offence to act as a ghost agent, so that people doing that could face arrest upon arrival in Canada.