what you probably want to hear:
easy, do it yourself, everyone has to start somewhere, price it at 5 dollars a square foot, you'll make tons of money, only take about a day to do.....
what you need to hear:
this is a difficult one to start with, you will definitely need help with some experienced hands if you keep it in house, pricing this thing could go a lot of different ways, plus design time, plus a place to install out of the elements, big and somewhat flat doesn't mean easy by any means
my best advise would be to pass on this, you don't seem to be experienced enough to tackle this one right out of the gate, even talking with the client you will not truly know what to say or even ask about their costly vehicle they are trusting to you not to destroy, i know everyone starts somewhere, but i think you will learn a very valuable and costly lesson if you attempt this one that you may not be able to recover from