front inner fender thickness

I checked AMD. They have inner fender patch kits. That might be easier for you. I'm not sure of the gauge though. https://www.autometaldirect.com/store/productdetail/205-2067-L/67-76-Dart-Fender-Patch-LH----71-2-Demon,-73-6-Dart-Sport?view=productdetail&stockNumber=205-2067-L&BOMReference=&selectedcat=&prod_cat=&desc=67-76-Dart-Fender-Patch-LH----71-2-Demon,-73-6-Dart-Sport