Need clarification on the rules

Is it legal to grab on to the corner of the field in the climbing zone I’m working on an fast and easy way to aim

Karthik answered this question here about the sides:

Basically touch one side, don’t grasp the sides/lip.

Similar answer here saying don’t rest on a ball on the field perimeter

and here in the updates to the manual:

But may of these are about the perimeter and high elevation, not shooting within the question. Using the sides is one thing but grasping them by more than one surface is another.

Hope this helps…](