This 2006 post by Roger H. is a good starting point.
story, as I've been able to figure it out is roughly as follows...
In the early '70s someone in St. Cloud
MN manufactured a trailer called the "Cloud". The Cloud
looked very much like the Burro
. In the late '70s the first Burros were produced in Plymouth MN, less than a hundred miles from St. Cloud
. Interestingly, the Burro was double-wall construction while the Cloud was apparently single walled. Burro was manufactured in Plymouth MN until the early 80s. Burro re-appeared in Sac City IA and began production in the mid 80s and had a production run until about 1990. Sac City saw the introduction of the 17' wide body along with the 13' standard Burros. Apparently the business was poorly managed and investors seized the molds and production equipment. Burro resurfaced in Escondido CA with new molds that were fabricated in Mexico in 1998 or thereabouts.
Again because of a variety of factors, Burro went out of business. According to the San Diego County District Attorney's Office, the owners ran into significant legal difficulties and seem to have disappeared, along with the molds and equipment."
I've heard 2001 or 2 was the last year of production for Burro Trailer of Escondido, CA. and know for certain that owners report trailers from '98 thru 2000. Photo of your trailer would allow someone here to at least assign it to the Plymouth MN/Sac City IA or the Escondido vintage as the trailers do have noticeable exterior dissimilarities.