I was taking another look at statistics, and seems I made an error when reading data from wikipedia, which I opted for in preference to Australian Bureau of Statistics (ABS) because it was easier and faster to read. Instead of getting the population for Yorketown seems I may have  read the post code. So my previous assessment of Yorketown and Kadina having similar populations and being at opposite ends of Yorke Peninsula was in error. The population of Yorketown only being around 685, whilst Kadina is 4857. The population of Maitland, located between these two towns having a population of around 1263 persons. It seems most towns in the Yorke Peninsula council district have populations less than 600 persons. The only other large towns seem to be Ardrossan 1136 persons, and Minlaton with 773 persons, both being in relative close proximity to Maitland. The result is that the population is concentrated to the northern end of the peninsula , and there is no large concentration in the south. Populations for the region are not so clear, as they may be combined with populations of adjacent towns or suburban regions.

Any case region still provides a source of data for critical population for a sustainable town, and dependency on adjacent towns.