Having said that this is the type of thing that is likely to get dragged in front of a judge, so the more foolproof way would be to retain 51% control or dual-class shares. Once you give up majority control to third parties, you can't really prevent everyone else ganging up on you and outvoting you.
And then you can have a fun lawsuit. Did the group persuade the 2% to vote their way or did they pay to control that 2%'s votes.
Yes. In tight-control transactions, there are a number of mechanisms.
Off the top of my head: specifying Board seats in the charter and requiring a supermajority or unanimity to change that. Voting rights agreements that delegate 51% of votes to one party. Turning all shares but two into non-voting shares, the two having 51% and 49% of the votes. Making transferred shares convert to non-voting. Transfer approvals.
Can this ever work? The PR group can control the 2% without nominally owning it.