The only thing that seems to take 30 minutes for me is replacing the batteries in the darn thing. Most of that time is spent crawling under the trailer to retrieve one that sprung out before I could get the cover on and rolled to the center of the trailer.
In all seriousness, I do cover the batteries with a strip of transparent tape, attach the door, then trim the excess tape off. Keeps the batteries from flying away.
(My install took about 10-15 minutes).