We visited Kaudulla in October 2012. Our guide reported to us each day how many elephants had been seen in the park so we were pretty certain of catching sight of at least one! There were only two of us, and because our driver was a qualified guide we didn't need to pick up a park guide or a ranger. Our jeep was very old - but it worked - and we were able to stand up behind the drivers cab and get a good view. Our driver was also sensible and didn't go too close to the water and so didn't get stuck in the mud. We saw one jeep with wheels spinning - presumably damaging the grasslands - and also frightening the animals away.
Helpful Hint: Go with a set of binoculars