In preparation for drilling the wingtip to the hinges, I cut a piece of XPS foam and inserted it between the hinges to keep them from flexing inward when drilling.
I installed the wingtip and taped it in place with some clear packing tape. I drew a line 7/8″ outboard of the row of rivets holding the hinge to the wing and marked lines even with all of those rivets.
Finally, I drilled all of the holes to lock in the wingtip’s position.
