That may work.
Have you seen the thread on NAXJA where the guy added head rests to the stock rear seat? It looked OEM when done. I can try to find the thread if you are interested in having a look.
The other option is to retrofit a WJ rear bench. I like that idea too. It is not a bolt in thing though.
I mention these options because I'm not keen on attaching headrests to a steel barrier. I initially thought I'd do that but after stewing on it for a while I decided that there would not be enough "give" in the event of a real accident. 2-3" of foam strapped to a cinder block still hurts when it drops on your foot.

Using a "normal" head rest setup means that the load is cantilevered off the back of the seat and it will have some give when needed.
I'm not sure what I'm going to do yet. But I'll probably need to do something soon since my little guys have both finally migrated to booster seats (without rear seat back).
FWIW, currently I have a Raingler rear barrier. It works well enough for my needs. I've been thinking about finding a finer rear cargo net out of another car from the wrecker. String that up behind the rear seat so that smaller items are constrained as well. We always try to have everything strapped down in the back but occasionally if in a rush a small item or two might be left unsecured. Or even think about bags of groceries. It would be nice to not get an orange in the back of the head if something were to happen on the way home from the store. LOL
Sorry to be a continual killjoy for your ideas - I really don't mean to be. Maybe I'm too fussy/anal about these kinds of things - you should hear the names the guys in our local 4x4 club have for me. LOL
:snorkel: