If that's the only thing that you want, then give the merit system time. Bounty cheaters will not get their accounts ranked up with merit system now and because of default trust members who are on the move to track merit abuse, they will get red tag those giving their alts merits or those who are into buying and selling of merits. Also, a default trust member can give them red trust if they are proven cheating a bounty campaign with multi accounts. I think it is enough countermeasure for that.