Hi Stef!!
I'm fairly new to kiting but will enliten as much as I am able..
The only spots I really know are mullaloo and pinnaroo point which aren't far north of joondanna. Not too far from UWA is leighton, however I've never kited there and couldn't tell you what the regulations are?? Best to find out from someone knowledgable first

As for car/camper rental, yeah they can be a bit restrictive.. What area are you planning to go in your trip?? You can get lots of places with any road going vehicle, but there are loads of places it isn't wise to venture without a four wheel drive.. So that depends on your plans, budget and setup.
Hope this helps a little
Bumstein