To make it more of a gameshow, they could introduce some sort of 'card' system.
e.g.
Yellow - HM once nominated + survived
Orange - HM twice nominated + survived - immuned following week
Red - HM 3x nominated + survived, automatically get to put a fellow HM up following week
Purple - HM 4x nominated + survived, can only nominate 1 HM from now on
This is to make sure theres variety + encourage game play!
Task done day before nominating;
White - given to the best performing HM/s (if draw), are immuned from being nominated that week
Black - given to the worst performing HM/s (if draw), deprieved from nominating that week
Cards could be introduced for a particular task or twist too, just an idea dont bite me head off!