There is always an exception, if it can be done someone will do it, of course in hot countries which tend to be nearer the equator, the arc is more overhead, hence the dish would be lying on it's back looking straight up, indeed there is a photo somewhere on the forum of someone with just that setup and it rains once per year for which he has drilled a drainhole at the lowest point
Well aware of that and it does rain in South Africa hence my tip of the drain holeThe OP lives in South Africa according to location details in the left pane in post 1.
Regards
See your is location SA.
Do not know why u want an upside down dish, but fully feasible.
Regards