Rules regarding summernats cruise cars?

[tankclare]

I have been toying with the idea of turning a vb commodore wagon into a custom summernats cruise car. Im talking cut off roof, short windscreen, custom rear seats etc. Now before I go out and hack up an old wagon and start playing. What are the rules regarding these sort of cars. Do they need permits or anything like that? It would be near impossible to register these sort of cars. I heard a while ago they just need to have lights and brakes but I know there would be more to it. Does anyone know anything?