I am not familiar with the 20 footer, but I bent the front pin on my 25 and tried to order another from D&R Marine. They did not have the small pin any more, so I used another large pin and drilled out the front hole. It works fine. There is a cotter hole on each end of the pin, that when inserted, it is outside of the walls of the tabernacle.
I am concerned that the pin you have is not the correct pin. It should not be able to slide out.
It is called a tabernacle, because it was invented by the Mormon Tabernacle Choir, and it is tradition for the Captain and crew to face it and sing "Shenandoah" to it, before each sail.
Or maybe, somebody thought it looked like the walls of a Tabernacle style church.