I know what a Fibonocci sequence is....what's a Golden Ratio.
Divide any number in the sequence by its succeeding number. Well, not exactly but it's a good approximation. Numbers further along in the sequence yield a better result. The height vs width ratio, found in many structures (e.g. Parthenon, etc) are found to match proportions in nature and supposedly are the most pleasing to the eye. Result - trailers (assuming 8 ft. height) shorter than 13 ft. in length look stubby and longer than 13 ft. look too expansive. OK, find this criteria in your shopping check list.