I would highly recommend Art Langston if you could drive to Osage Beach for lessons--Art plays bass with clarinetist Len Zimmer at the Country Club Hotel, has been a professional jazz player and instructor many years. Taught bass at UT Austin. He lives in Jefferson City, but plays four nights a week at the Lake and has several students in the Lake area. Check him out at
http://www.bassace.com/
I moved from Bass Guitar to upright six months ago, and have been taking lessons from Art since then--he is a perfectionist when it comes to technique, but has a great way of helping you figure out your musical goals and constructing a lesson plan to meet them.
He also has extensive knowledge of both classical and jazz literature.