I've never heard of anybody just being stopped by the police for no reason (compared to Vietnam, where it happened to everybody ), but yeah, if you're in an accident, you'll be assumed to be at fault.
Be sure to get a "rider" -- not a passenger, but a special provision on your traveler's insurance that will cover you in the event of an accident while pursue a dangerous activity like motorcycling.
If you bang into someone's car, you'll end up paying several hundred or a thousand out of pocket -- painful but survivable. If you bust up your spine and need to be med-evac-ed to Thailand or Honolulu, somebody is going to be out tens of thousands of dollars, and without the motorcycle coverage, it's gonna be you!
