For the test we just put books or a piece of wood under the legs. I have a much smaller table in my White Room, (soundsound.ie). I intend to cut a little off the legs. The tilt was quite small, not enough to make things slide off.
10-15 degrees maybe? Here's the desk in situ. Don't know if this pic is before leg adjustment or after.
Glad you found it interesting. I found it a bit of an eye opener that such a smallish surface, not even flat really with all those things on it, can wreak such havoc.