Bought the Walmart-sold bracket and have had it on the car since a week after the original post. Working perfectly. It's staying level after using Locktite as suggested from many sources.
Cheap, easy to install and much better than the aging holes in my bumper which were no longer (if ever) secure for the Porsche provided/sold bracket.
Would recommend this to anyone (especially with an aging car/already lost a plate or too).
Andrew