In some states it may be legal to haul a load up to eight feet wide without special permits. The widest load I've carried was 25 inches wide.
Show me your stupid wide load, you know you want to. I saw a great thread here recently about cargo bikes in China, which gave me the impression that it's common to make a bed above the fenders that extends well beyond on each side. Any Chinese peasants or other crazies reading this who roll that way?