I have previously seen discussion on this forum about this. Well it seems Toyota doesn't want it open. The "door open light" stays on.
Had to transport some 10' long evestrough home. If set on the dash they stick out the rear window about 3", so no flagging necessary. If you transport anything long like this, use a towel on the dash and rear door, and tie it in the rear to a cargo hook on the floor. Don't want any oopsies!