I am going to purchase a boat from Oklahoma and bring it to Texas i know the seller has a title for the boat and motor but nothing for the trailer. Will pose an issue for me to get a tag for the trailer? Or is it just paperwork at the tag office.

I think you just need a bill of sale for trailer

Boat and motor are TPWD, trailer will be your local tax office. Bill of sale for trailer along with trailer capacity should suffice. You likely don't need to title the trailer, just get it registered.

tag office will have the paperwork for you. the bill of sale is all you need. and get the title for it.. it helps when it comes time to re sell.

the tpwd has all the forms for the boat and motor. i'd take a pic of the serial # on engine and the HIN# on the hull just in case you need it
when you go in to the tpwd office.

I bought mine in La.. La. does not show weights on their trailer titles so I had to weigh the boat and trailer and then while in the tax office deduct the boat and motor weights. I have heard that some tax offices insist on getting weight of trailer while empty. Fortunately I did not have to go through that. I also had to get it inspected. Inspection might have been due to the size. It was all a pain because the first time they only said I needed inspection. TPWD requires a pencil tracing of the boat serial number. If it is not legible then a GW will have to inspect. I am not sure that LA even requires a plate on the trailer. Mine did not even have a mounting bracket for one.