High Alt landings
You haven;t specified the payload. Moreover, a helicopter designed for the conditions you mentioned would probably have poor performance at. say, sea level. There is always a pay off. Designing choppers for specific tasks is not an insurmountable problem. However, the more demanding the requirements, the more ad-hoc the design and the less likelihood of its finding a place in general commercial use.
The Heli-pad size would dictate the track of the bird, but what of the rotor disc? If you want a smaller rotor disc, the disc loading (with associated issues) would be high.