Hi. I don't want to be negative here but having been involved in several Formula Student projects if you can get a wing to create any sort of useful downforce at the speeds these cars reach then you are an aero wizz. All you are going to really do is add unnecessary weight. Having said that as others have mentioned it really needs to be formed in two halves, substantial reinforcement/ribs added and the two halves bonded together. The supports also need careful thought and design. If you are not confident that whole wing fitted to the car wont support your full weight then it isn't going to be strong enough. (assuming it actually creates downforce)
Also remember if you do manage to design something that works you will also need something at the front to balance things. otherwise the front of the car will become light causing understeer and reducing braking efficiency etc.

Good luck with whatever you decide to do.

Warren

Carbon Copies Ltd