During my visit to the Grampians National Park, I chose to stay at Plantation Campground for most nights. This free campsite is spacious and conveniently located just 12 minutes from Halls Gap, making it a great base for exploring the park. However, be aware that it lacks facilities and reception, so you'll need to be self-sufficient. The access road is a dirt track with some corrugation, so take it slow to ensure a smooth arrival. For more options, you can check out other free campsites around the park using WikiCamps.  While at the campground, take advantage of the clear skies for some fantastic stargazing; the night sky in the Grampians is truly spectacular. 

If you need to freshen up after your adventures, you can use the showers at YHA Grampians Eco for a $10 fee.