My 400 isn't parked on level enough ground to give you a good measurement currently, but I have these photos from my salesman when I was long distance purchasing my camper.
It is 18.5" to top of ball on pretty level ground...you can see the attitude the 400 is at in the distance photo, when the measurement was taken.
I've used both a zero drop and am currently using a 2" drop on my Honda Ridgeline and it looked very level with both...
By the numbers, the zero drop should be perfect for my application, but I think it tows better with the 2" drop...and still looks perfectly level to my eye. Point is, I think you don't need to be perfect, just within a working range, and preferably a little downward angle is safer (from a sway perspective) than an upward angle.