Texas Tax question for out-of-state (LA) small business

Hey everyone. I own a small business that is run out of my home in Louisiana (S-corp) where i provide laser engraving services. I plan on doing a few art festivals in the state of Texas (maybe 2-3). I also plan to attend the TX state Ducks Unlimited convention as a vendor. I make a few wooden products with ducks on them that they like to buy. I do have an online website where I ship nationwide but I'm still really small. I don't ship out of state very often. last year, I did sell about $12k work of products to DU in TX, but that doesn't happen often either. When talking to my CPA, he mentioned that if I would like to travel to TX to sell products, I would have to register my business with the state of TX, have a TX-registered agent, and create a NEXUS. this costs about $1000. Is this necessary for the amount of time I'll actually spend in TX? Thanks for the help!