Ok so i just jumped in and tried something. Cut a frame for my tweeter, put it on the side view mirror screw cover and fiberglassed it.
(Test fitted the tweeters in this pic)
Then I threw on some body filler to smooth it out and give it a little more strength.
The hardest part was when the body filler was dried and sanded, I have to repeatedly go over it with spot putty to fill in little cracks, holes and such that didnt smooth out. I would spot putty, sand, prime and look for more holes after the primer dried. Did this about 8 or so times till i was satisfied enough to paint it.
Now this was like a test and my first attempt so its by no means perfect obviously lol. I wasnt concerned with smoothing out the bottom tab piece since its hid behind the door panel. After I slid the tweeter into place I took some caulk to fill up any space that might have been left around the tweeter then painted that with some touch up paint to match. You can see the difference between the spray paint and the touch up paint becuz of the camera flash but in person its really not THAT noticeable. For me, these are good enough to use and serve their purpose, but surely next time i'll know more of the dos and donts as well as taking my time a little bit more.
Will post pictures of it installed once i get around to it. I still gotta finalize the other side also