I also do a right-turn, sometimes on red, onto a shoulder where the traffic on the road is 40 - 45 MPH.

I wait for a gap, so I don't freak the on-coming motorist out due to the small reaction time. It's bad to have lateral motion in front of me (as a motorist) with little or no time to assess and react.

If it were 30 MPH, I wouldn't bother.