Fitting out a Ford transit van as a camper, i want to do the change of usage. and can fit it all in, but it just says MUST HAVE WINDOW IN THE SIDE. but as far as i can see it doe not say how big it has to be to count as a window, and if window in side sliding door counts, i wanted to keep my van a stelth as poss, so i only want to do the smallest size i can

 thx