If any of you are readers of FLYING magazine then you'll be familiar with Peter Garrison and his Melmoth II. It features rear-facing back seats.
Another comparison point is the Glasair Sportsman 2+2. When originally released, the forward-facing rear seats were placed at the aft end of the cargo area and, as a result of the fuselage taper, were limited to carrying small people (5' or less, give or take). Glasair has now released rear-facing back seats which can accommodate full-size adults, thanks to the greater headroom available further forward in the cabin.
With respect to head/neck injuries, head support obviously is key in preventing injuries. However, if you stop and think about it for a moment you'll realize that our heads have no support at all to counter the major deceleration forces in a crash, with frequent severe injuries resulting from front seat occupant's heads contacting the instrument panel. In this case, forward-facing occupants are best protected by good seatbelts (even ones with airbags). Aft-facing passengers might actually have an advantage in this regard. The fully-supported aft-facing seats used by flight attendants in many airliners are likely the safest seats in the airplane from the perspective of head/neck injuries. You don't want to even think about the risk to those same flight attendants posed by unsecured trollies, cutlery or coffee jugs!
With respect to rear-facing seats for photography, Marc Cook, the former editor of Kitplanes magazine had a single rear-facing back seat in his Glasair Sportsman; that seat was purpose-built for photography. With the cargo door removed, his aircraft proved to be an excellent photography mount, with many of the photos taken from that rear seat appearing in the magazine.