Determined location of wingtip “oil canning”, laid out and epoxied in backer rod from Lowes to prevent this flexing of the wingtip. Other builders have noted that their paint has cracked from someone leaning or pressing on their wingtip. Some have also seen vibration of the wingtip in flight. Decided the 1/2” rod is too large so will get the 3/8” for the rest of the installation.