There is a rudder lock that someone is selling.
http://www.rvtraining.com/html/gust_lock.html
Tim Olsen has one in his plane but I think he modified it slightly so that it pushed against the rudder pedal and not the master cylinders.
I will take a picture of the one I made next time I am at the hanger. It works perfect. I bought a small expandable roller rod and added some PVC fittings. It wedges between the pedals and the floor beneath the stick and locks in. I think I spent $25.00 on parts and I made it 15 minutes before a weekend trip. I will sell my prototype for 3 easy payments of $19.95. haha
For the ailerons and elevator I use the seat belt with a couple of wraps then lock it in.