Been there, done that, got a t-shirt.

See: http://www.tpwd.state.tx.us/fishboat/boat/owner/titles_and_registration/

Click on: Not Currently Titled and/or Registered Through TPWD media download(PDF 231.9 KB) -This matrix provides the requirements for titling/registration of a boat/outboard motor which is currently not titled/registered through Texas Parks and Wildlife Department.

I have a similar situation, but was told by TPWD to look at getting a bonded title. I posted on here before about this and got a lot of the same comments. I don't need the boat nor the headache.

If you know someone in Louisiana, they can title it with only a bill of sale. Then they can sell it back to you.

I bought a cheep jon boat and had to figure this out. I lucked out cuz it was so old it had ZERO identifying marks on it. The texas numbers or hull ID can all be traced and they make it so that you MUST find the last title holder. If it has no ID on it then you get your buddy to put on the form that it has been in the family for years and has always been used on private land so it has never been registerd. After a game warden inspection you get a new hull ID, TX numbers and a title. Trailers are easy, call it home built.