Personally, as you have said, as you have chosen to camp at two places within half a hour of one another (rawnsley and wilpena), I would have chosen to go somewhere a bit further away, like Gammon Ranges NP for 2 or 3 days, instead of doing day trips up to there.
If you want a caravan park experience more, stay in the park at wilpena. If you want a bush camp, go out the back at rawnsley,away from their cp.
You will love it all either way.