What are the dimensions of the A320's wingtip fences?
Dimensional information can be found on Airbus's Airport and Maintenance Planning Documents for the entire product range.

You will have to do a little digging and calculation to find the sizes of the wingtip devices but they are there.

Specifically, on the A320, subject 2-3-0 lists the height of both of the bottom and top of the wingtip fences relative to the ground, and 2-2-0 provides dimensions from the top.