"KingstoniPad aims to address this by maximising the use of space, minimising environmental impact and encouraging a less car dependent lifestyle."
Or you could just tip a car on it's side and rent that out. At least it would have bloody windows.
And the use of the name iPad is sure to get someone into trouble if Apple ever launch a touch sensitive sanitary towel.
The lack of windows needn't be a problem though. The TARDIS doesn't have any windows and that still looks pretty spacious on the inside.
Maybe a CCTV camera wired up to a plasma screen would do the trick...