This is a shot in the dark, but keeping in mind that many, many trailer manufacturers will do custom modifacations for customers just about any companny could have made it.
Being that the trailer is not marked and I am assuming there is no title or you would know who the manufacturer was, I am going to just put this out there.......
I see you are in Kentucky, several years back there was a company in Bowling Green Kentucky. They were apparently having financial distress issues for sometime. The company had closed shop and skipped town with their supplies, deposits and belongings, only leaving an empty warehouse. They had a rocky past. They did manufacture trailers, and randomely filled orders for several years. Point being, of those trailers that were manufactured, a very large portion of them could never be registered and never had titles. So they were ultimately rendered useless for long hauls on highways or for anything more than an emergency.
There are some individuals with metal fabrication skills that can do a heck of a job and there are companies like the one I mentioned. Any legit trailer should have a metal plate with trailer info like the axle weight limits, total vehicle weight, title number, manufacturer ID #..... (or at the very least a place where that plate once was, in which case, if it were removed/missing it would make me question if it was stolen). The plate is usually near the front of the trailer towards the tongue.
