Mounting the latch on the cab instead of on the door could present a problem with confusion in opening the door from the inside in a panic emergency exit situation. I'd advise mounting the latch on the door as intended by the manufacturer and the stud to be mounted in the cab opening. You can then use your original inside handle or any aftermarket or donor car handles on the inside of the door to open it. You would then run an emergency release cable down the inside of the door and have an exit at the door bottom for access to the cable. You could also make a steel rod and a bell crank setup to release the latch. Run the rod straight down to the door bottom covered in rubber to prevent rattling around. An access hole at the door bottom will allow you to push the rod thus releasing the latch.