Whilst most tourists go to Crete to stay in rented accommodation, intrepid explorers, by car or on foot can make a home wherever they lay their hat. Officially camping outside of permitted locationso is not permitted, but this doors not seem to be extensively policed. You will regularly find caravans tucked into quiet corner of beaches or woods, more often than not wealthy Greeks from the mainland or other Europeans roughing it around the islands.
A more conventional approach is to use the handful of perfectly good campsites on Crete. Mostly situated on the south coast, fairly modern and they provide more facilities than a lone tent.