One of the issues with this is the certification criteria to claim hover performance - civil flight manual performance is not based solely on the ability to hover - it has to be a height from which you can transition into forward flight over a flat surface and when hitting the ground vortex roll up (for lack of a better word), you won't descend and hit the ground.
Also, controllability has to be demonstrated in all quadrants to 17 knots of wind.
The problem is to find a way to demonstrate / test for these conditions.
And a more practical problem, if you're coming in to land at this helipad at that altitude - you'll need more power to stop the rate of descent than you will to hover. Similarly, to takeoff without a level surface to fly over, you'll need more power than to hover over the small surface. But - how much more power???
tricky problem, and one where the certification criteria don't help much.