2014 Prius Five Add Aftermarket Moonroof

I bought myself a Toyota Certified 2014 Prius Five with every added feature available and with the advanced technology package. Unfortunately, Toyota does not make the Five trim level with a moonroof option. When I bought the car the salesman told me that is because the Prius Five has 17 inch wheels. I am not sure what on earth wheel size would have to do with the ability to have a moonroof. I am thinking about having an aftermarket moonroof installed on my vehicle. I have found a local place that does very high quality work and they say they can do this. I am not talking about the solar sunroof that some Prius's have. This would be more of a traditional moonroof. Is it safe to do this? Does anyone know what the car salesman was talking about when he said that 17 inch wheels can not have a moonroof? I did buy an extended warranty with the vehicle. If I did this would it void that warranty?