I avoid any type of grade if at all possible.
I have scraped the front splitter. Not fun. But on the bright side it was a good thing that it was not painted from factory! I will park blocks away from a business if they have a parking lot with a grade. I just avoid them all together.
I guess you could try going through the parking garage and come up to area and have your passenger "eyeball it" for you? Hopefully someone can chime in on this one.
-Ordered 2014 Shelby GT 500 Black with stripe delete (Putting on our own silver stripes :D ) 820A, Shaker pro, Order date 2-8-13