Note the Stealth bomber: for Yaw control it uses airbrakes at the wingtips... doesn't even HAVE a rudder. It uses elevons.

Note the Gremlin Combat models: they have dual fins... no rudder, and uses elevons.

Note the Zaggi: (considered by some as a trainer in flying wing configuration... ) It just has some wing tip fins (if you bother to put them on..) Again... elevons.

They ALL do it this way because... it works.

There are others...