Sounds like the Anglers Association is entrenched with the interest of the charters there. Catching big bass is big business, but as we do all to well in North America, we don't put reasonable limits on consumption until the problem starts hurting local economies. It would be a hard sell to align the "immediate" interest of the fishery with the charters, and thus, a hard sell to the MNR. Although, long term, their interest are all ready aligned.
Write a thoughtful letter to the MNR for their condsideration including your points mentioned above, a case study proving slot sizes working, impact analysis on the local economy and, in closing, advise as to a petition being formed on the matter. Send a copy to the MNR and also your local press. Get statements from the anglers association and those petitions filled by as many as you can. Update the press and maybe they'll pick up the story, get some spotlight and take it from there.
But that's just grassroots wishful thinking