Ekh
Elio Addict
Better to design one in, so it fits with the rest of the vehicle and is visible without blocking either instruments or forward vision. Add-ons run into problems that a little design forethought can prevent.+1 to the people who said backup camera!, I believe it will be a great addition and I plan on one either way, especially with no back window to see out of, not to mention the ease of hooking up a trailer.
That said, I understand that things cost money, and I will shell out for a camera -- I'd just as soon the space for the display was allowed for in the car's design.