Is it wrong just to do part of a door panel in fiberglass for a speaker mod? Will the panel be able to support the weight or will the entire panel have to be redone?
You can do it any way you like, and yes the door panel is strong enuf....but that all depends on what you have in mind as far as what kind of panel you plan on building.
do whatever looks good to you... not a matter of panel supporting anything as much as panel being attached to rigid surface that should be your concern...
that was the point of the question, whether or not only doing half the door would provide enough support