I have not done this round trip for a while. Its very interesting amazing country side; mining; beaches; forests. It is probably about 1500-1800kms. I have a Tesla so it's a challenge I guess (charging). But that just needs some planning. Room for one passenger in the car.

Plenty to see; farming country, old mines, old settlements, Gold super-pit, beaches, beaches beaches, land of the giants (forests). I will be doing some planning to work out the route (but am flexible) also dates I am flexible with.

Probably the minimum trip time is 4 or 5 days: 1 day Rockingham to Kalgoorlie with a side trip to Hyden (Wave Rock) on the way and overnight. Visit the Gold Super-pit; One day to Esperance with overnight (National Park and beach); One day to Albany with overnight (and somewhere half day at a place like  L'Grange national park on the beach); One day to Bunbury maybe an overnight there (or to Dunsborough instead with an overnight there; or maybe push on to Perth. It's another 3 hours from Dunsborough to Perth.  Best to Google earth these places.

Accommodation : there are plenty of caravan parks backpackers and cheaper motels. Maybe even 1 or 2 nights under canvas at a caravan park. Separate rooms or bunks or separate whatever.