I found a wheel on gumtree, its from a non-phev model and has slightly different spokes but it is the same overall size as the phev wheel. I think I paid $100 for it. Unfortunately, there is no way to store it under the car, it just sits in the luggage area in the back taking up lots of space but you crush a lot of clothes,sleeping bags, etc into the centre of the wheel. I only carry it when doing country trips and I as for safety I run the middle rear seat built through the centre of the wheel.
I went through that exercise calculating the benefits of selling my solar power and then buying it a cheaper off peak rate but thought the differences in cost are negligible but importantly I feel much better driving around on solar power.
Enjoy the car, and look at all the info on this website there is lots of great info available. Finally keep on eye on the voltage of the auxiliary battery, you will find on this forum that most of the problems people have had is when the battery starts to lose charge. I had to replace mine earlier this year and went through the exercise of trying to find a replacement. However, once I looked at the old battery I found it was standard exide battery, I managed to find a similar battery in the local battery shop.
By the way I live in Sydney at Hurstville.