Driver's AIRBAG Questions

I have a question concerning the airbag in my Toyota Hilux 4x4. I live in the mountains of Colombia, and the roads in our location are unpaved dirt and VERY rough. Many holes, big rocks, and washed out areas. Several of my friends have hilux 4x4s, and two of them have had the airbag unexpectedly deploy while driving. Neither will admit it, but I believe they were driving very fast, and hit a large rock or a deep hole that shocked the truck enough to fire the airbag sensor. Needless to say, I don't want to have this happen to me. I would like to install an airbag "disconnect" switch to disable the bag when I'm in the mountains, and be able to switch it back on when I'm on the paved highways. I know I can figure out how to do it, but want to know the BEST way. Should I just kill the power to the entire airbag circuit?? Or just to the sensor and/or the bag itself. I don't want to accidentally activate the bag when I operate the switch. Airbags are not required here. They were an option until about 3-4 years ago. Now most cars have them, but some (mostly China imports) don't. So I could find a non-airbag steering wheel for my model year, and just swap it out. However I like the safety the bag provides in city and highway driving.
Any help and suggestions will be appreciated.

- JAMES