I spent 5 years in NZGS when they had significantly more movements than they have now and breaks were never a problem. We simply broadcast, "Gisborne Tower off watch for the next XX minutes" and went downstairs to the little boys room or the airport cafeteria for some food. Never a problem!
Whatever you do, ALPA, don't lose public support by insisting on rostered, specific-time breaks at small units. If a scheduled public transport arrival is scheduled in that time, you won't be making any friends.
On the other hand, if movement levels are getting beyond what one person can reasonably handle, then a call for increased staff is in order.