Is there a likely completion date for the multi storey carpark yet? That would indeed be an epic location to spot from. Any chance of them setting up a little food / drink area to make a bit of money out of people coming to visit, or by the roof do you literally mean the very top out in the air?
Judging by all the cars that seem to be at the crashgate you'd think it would be busy enough, especially during summer and school holidays. People would definitely bring their kids up if such an 'attraction' was officially open.