I don't know if the '83 is much different than my '69, but on mine they can be accessed from the inside under the side drape behind the seats. The top nut is fairly easy to get to, the bottom one not so much. I had my wife reach that one, as my hands were a little too large for the space.
The badge sits on a semi hard rubber pad and the badge has two posts which are inserted into a plastic receptor. The receptor is inserted into the fender body and the posts expand the plastic receptors to hold the badge in place. There were no screws on mine and they were gently pried up to remove. If your 83 is similar to my 84 than its near impossible to reach from the inside.