We have a couple Ritchies with 4 holes and one with 2.  We took 1/2 the floats/footballs out.  They'll ice over in nasty weather but usually cold alone won't do it.  It takes an overnight wind to freeze them up.  Ours are somewhat protected because they're nearby buildings but not "sheltered".  We also have a 250w doughnut heater in each one in addition to the heat tape.   Taking 1 or 2 floats out has resulted in less trouble  Water level is set so remaining floats are down from lid at least 1/2".