It appears that there indeed is a "left" and "right" wingtip orientation. If you look at my original photo, I had to take the antenna apart and reassemble to use it on the lower surface of the left wingtip and still have the point facing forward.
I drilled out six nutplates and sandwiched the short side of the antenna underneath. The nylon clamps were used to guide the lighting harness.
A test on an ILS approach proved dramatic improvement of the localizer signal. The glideslope was a bit late to unflag, but steady once acquired.
Overall a huge success and another gripe removed from my list. Thanks for all the help I received from VAF.
PS: I have now purchased two flying RVs. I have come to realize that if a builder makes a mistake, and doesn't realize that mistake, AND does all the subsequent condition inspections, that the mistake will never be detected. Thus I would recommend that even if you do possess a repairman's certificate for your airplane, have some additional RV knowledgeable eyeballs observe an occasional annual inspection.