Roof Vent Installation

I am slowly making our little Featherlite 6X10 that we haul our motorcycle around with a bit more livable and have recently decided that a roof vent would be my next little project. I am looking for some installation assistance that will have it fitting and looking nice between the 24" metal braces that support the roof.
Also if you have any recommendations on a particular brand with a fan it would be welcome.
Thanks!
Also if you have any recommendations on a particular brand with a fan it would be welcome.
Thanks!