Seems to be more experts here than ever!
In order for a single pilot to operate an approved single pilot helicopter from a seat other than the designated Pilot's station (check your Flight Manual): you will have to obtain an STC to permit that function. This of course, ensures such things such as the manual release, controls, etc, are within your control.
So in order to longline from your 206/205/212, etc; you will need one more minor item than covered here.