I tried going the correct route with a jetski trailer a few years ago, even with a bill of sale from the previous owner stating the chain of ownership of the trailer and that it was now mine and not stolen, i ended up registering it as homemade, which took about 1/10th the time of getting it done correctly. The second trailer I bought (2-ski trailer) i was able to get a correct bill of sale from the owner listing it as a manufactured trailer that was not large enough to title, and even with all of that, it still took at least twice as long before i had my paperwork in hand and was headed out the door.
the state of texas makes it really hard to transfer legal registration of trailers under 2500lbs or whatever the cutoff is for titling. the only thing that proves you legally bought a trailer is a copy of the previous owner's registration and a bill of sale from that owner. lose that and its just way easier to register it as a homebuilt trailer.