Am I correct in understanding that the CC shop said the strut that holds the door open is causing 4-ft. of stainless screws set 4 to 6-inches apart to break off, the same CC shop that incorrectly installed the wrong screws 8-inches apart in the first place?
Maybe I'm missing something but I can't see how the strut could possibly exert enough pressure to be causing the problem.
The only thing I can think of is that all stainless material is not the same and possibly you have very brittle low-grade screws that have failed. If you have any metal fitting held under tension, vibration will, over time, cause the part to fail.
I would check the door to see if where it attaches to the frame it is square and fits in the opening without the screws having to pull it into allignment. If the attaching screws have to "suck it in" over time, they will fail. The bay doors have a problem of delaminating, that is, the outer skin comes unglued from the frame. This can cause the door to rack or go out of square.