In my uneducated mechanical intuition, it's the footer base that would be most likely to fail if anything, with the upper two bolts' flat portion shearing off. Luckily there's 4 of them per brightmount so it would probably not all happen suddenly, one would probably go first and get caught by the others for a while.
The extendible lower (now upper) arm would also be subject to a more significant compression force than usual. It would have been better to do this with the non adjustable version. Additional holes could be driven through the extension parts and bolts placed through there for more strength. I am doing this anyway cause I bought the set screw version, and the set screws were just obviously a bad idea in the first place.