You've probably already done this, but put the word out at the horse sales. Especially the one in Magnolia. So if they get any tack in that matches the discription maybe you'd have a chance of gettin it back, and also of catchin the idiots that stole your trailer.
We were in and out of the Anderson Trek trail ride this weekend, while there, I kept my eye peeled for a trailer like yours. Didn't see anything tho. But I was lookin!!!