Jeremiah,
There are at least four good watchsmiths in Houston who provide service to our members' watches. Which is good for you may simply depend on where you live in Houston and in which part of the city is a conveniently located watchsmith.
I use the watchsmith at The Masters's Workshop, 1410 Blalock, 714.468.1472. They have always been very competent and reasonable. I have never asked them to waterproof a watch, however; so I don't kniow their capacity to do that specific thing for you.
I know there is another in the Sharpstown area and another in the Galleria area, but I don't have the specifics on those folks.
Come see us at our next GTG in Houston. If you haven't sorted out a watch repair service supplier by them, several members at the GTG will be able to provide you alternatives.
Best wishes and good luck.