WA travel advice please Hi all, Myself and a friend are renting a campervan for 6 weeks from the 22nd of December from Perth

We ideally want to do north and south WA but wondering has anyone done something similar and what would be the best split.
Someone posted this really helpful infographic for south (thanks) if we spend 2 weeks doing south, is that enough? This would be the main Christmas period. Should we try them drive as far north as we can over a couple of days and then do the stops on the way back to Perth? Would you recommend going all the way to Broome or just leave it at Exmouth ? Depending on how long we spend south, we should have about 4 weeks for up north (or less if you recommend south for longer)
Can also do north first either
Finally, campsites are all looking pretty expensive, all powered sites from my initial look are 60+ night everywhere, is wild camping big no no?
Thanks so much in advance – all opinions welcome