Like Brian, I never like to be critical of another persons work. We all have different ways of approaching things, and I have seen some unorthodox things work in the final analysis. But since the discussion has been opened, I have to agree. Fiberglass bodies do not like to flex at all. The majority of their strenth comes in from the floor and upright stringers. The body relies on these to be strong for things like door jam alignment and rigidity.

It does appear that this strength has been compromised by cutting so much out and patching metal and wood into the openings. Pictures only tell so much, but that seems to be the case.

Don