As you already know. Even in the heat of Texas it can get chilly during a storm. Light foul weather gear for summer, and heavy for winter. Your own GPS to play with, small flashlight, but powerful. I use to wear a small torch on a breakaway tether on my neck. To watch the windex, sail shape, and peek around the boat. You might want to take your own chart, so you can practice, and mark them up.
My brother shows up with a packpack for a 2 -3 week trip with us. Several swimsuits, t-shirts, shorts, and something long to cover his legs in case he gets too much sun. Most people make a mistake of taking the dresser draws with them. It's a delivery, so maybe 1 nice shirt for arrival.
If you do the chart, then take the paralell bars, dividers, and pencils. Don't forget your toothbrush, and deodorant too!!!!!!.