I'm struggling with what to do about the door panels in my 79 Bronco. I
have installed seats and console from a later model and of course
nothing from the 70s trucks matches, so I have to make my own. The
thing is, while I'm doing this, I am installing the sound system. The
front speakers aren't going to work with factory door panels, which is
ok, but I need to either modify them or make new ones so I can use the
speaker grilles.

I've made the rear panels of 1/8" hardboard similar to package tray
material, but seem to be more rigid and sturdy. I will cover them in a
2-tone vinyl. The center sections will be sewn vertically every 1 or
1.5 inches to a thin padding. It's not pleated, but I don't remember
what it's called. It's kind of like the insert areas on many 60s cars' seats.
Anyway, then this will be sewn to a contrasting, but matching border. I
think they will be MUCH better than the faded carpet-covered wall
paneling that are there now and actually will look like they belong.
The front ones will need to match, and have a flat area where the
speakers mount in the factory locations.

Here are the options I've thought of:

Make a Plaster of Paris mold of each door panel.

1. Fill in the speaker area of the mold to make it flat and blend
it into the contours of the unaffected area. Lay fiberglass to make a
complete new door panel. Difficulty involved is making the mounts for
the door panel clips.

2. Cut out the speaker area of the door panel and place it back in
the mold. (This might only require a mold of the affected area.) Fill
in the section of the mold where the door panel is cut out to make it
flat, blending it to the door panel to make a smooth transition. Lay
fiberglass to make the new speaker area into the back of the door panel.
This method allows me to use the factory door panels with a new speaker
area molded into it.

3. Use the same 1/8 board that I used for the rear panels. For the
armrest/latch cover, I could use the molds to fiberglass just the
armrest/latch cover part of the door panel, which would allow me to also
fiberglass in some mounting bosses to screw into from the back side of
the panel. An alternative to this would be molding my own armrests.

In either of the above methods, I would still cover them in vinyl to
match the rear panels. For the first 2, the inset around the window
crank that extends up above the armrest and the inset across the bottom
(grille-type area) would be the same pattern/color as the center of the
rear panels. The edges and the center area (armrest/latch cover
portion) would be the same material as the border trim on the rear
panels.

For the 3rd option above, they would be just like the rear panels, and I
would cover the molded armrests with probably the same material as the
border trim.
For insulation, I'd be able to use the factory pads for the first 2, but
would not be able to insulate the 3rd method. This is not a problem for
the rear panels because of the bedside cavities.

Am I going overboard and thinking too much into this? Is there an
easier/better door panel option? If not, which of the above would be
the best route?