I used cheap 1/8" paneling. I don't have any curves in the 37. The problem with masonite is that you don't want to get it wet.. It separates. All it is is tempered card paper. On the back side it is a good idea to run a vapor barrier. it also helps to keep the water from getting to the board. I am also thinking of using those steel clips that have a 1/2" head, and you have to drill a 1/4" hole in the door to push it threw.. i like the idea of the plastic plug though.. I had them on a Honda I did before the 37.
What is the name of that spry glue that you got at Wal-mart?? I to am on a budget.. That is why I am doing all of the work myself. Not looking for the Riddler here.. it will look good though.. Al