look at the driver side, it doesn't have to be that thick, some heavy scrap sheet metal will do .... use the mirror arm to mark hole position on the door, then mark the reinforcer thru those holes
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics