I just went through this in NC with my boat that was purchased in the fall. It was a pain in the ass. I don't know Texas' rules, but here I had to go to the DMV to get a checklist so I could figure out what was needed. My trailer did not have VIN as it is too old, so I had to take it to the law enforcement inspectors of our License and Theft Bureau after receiving an NCX #. I then had to get an insurance bond through my insurance company for a percentage value of the trailer. They had me sign an affidavit saying it wasn't stolen, had me permanently affix the NCX number to the frame of the trailer in two places (I engraved it with a Dremel) and bring it back for an inspection. I then went back to the Tax and Tag office of the DMV to pay the tax and title fees so that I could get the plate. It took me taking half days off of work on 3 separate occasions to get it done because I essentially had to create a new paper trail of documents since it was lacking all of them. I will never buy another boat in NC without first asking if they have the proper paperwork for the trailer. Do what you can to get as much info from any sources first because it was a real headache.