First time I have ever seen a specified measurement as to the width of the trailer and the necessary length of the tongue.
Whatever the case, one important factor is to NOT load too much toward the front of the trailer. A few yrs ago, on the interstate out of Milwaukee after the 100 yr HD anniversary rally, I got stopped in traffic behind a Harley with a trailer that had left the rider semi-concious and stunned in the middle of the interstate.............He was damn lucky, that the car behind him didn't run his azz over........The bike ended up in the roadside ditch upside down.
The car driver indicated that the trailer started (fishtailing) and it just threw the rider off the bike before he could even react. I think he had the weight wrong, whatever the case, I have been very skeptical of ever using a trailer since that scene that I witnessed.