My wife Jen has been asking for a headrest since day one. It's on my list for a rainy day. My plan is to fabricate a lightweight frame that slips into the seatback brace slots on top of F-705 and attaches at the top to the back of the roll bar (tip-up canopy, I know you have a slider...sucka!).

Just kidding.
Obviously the bottom will release quickly by virtue of slipping into the slot, and the top will be easy to release as well since it will have a knurled knob on the bolt. Unscrew that, slip the thing right out, and you can load bags.
On the slider I assume you'd want to run "legs" down into the seat back for support.
)_( Dan
RV-7 N714D
http://www.rvproject.com