Chris at TheGreatness.com (a fantastic Donair resource, btw!) responds:
Dunno. I would think, given the Mediterranean emphasis on salads and the North American "chicken caesar salad" phenomenon, that such a salad would make some
sense. It's a natural evolution from the "doner kebab" and green salad combo that is common in Turkey and, by extension, in European towns with large Turkish populations. But Canadian donair has a well deserved reputation of being the food you eat when you don't care about healthy eating. How do you mix that with the healthy clientele that usually wants a salad? Maybe it would work, but it's one more item on the menu to keep track of.
So far, none of the other leading donair innovators or commentators have replied to my request.