I have the standard Rocker with the struts and the pillion seat. It could work as a backrest IMO if you're a bit taller than me (I'm 5'7"). I sit a little up on the seat to reach the forward controls so I'm missing the front edge of the pillion pad by a couple of inches unless I really lean back. I really just use the strut system for the luggage rack and I put the pillion seat on if I want to carry a sissy bar bag. Just like Rocker C's smaller picture.
Nferr - are you using the stock bars? Hubby's about 5' 10" and we're installing mini apes so I'm hoping that will sit him back some.
Yeah, I use the stock bars. I like the stock bars, but I do lean forward just a bit which I prefer because it's relieves any back strain for me. At 5' 10" he probably will be able to use the pillion as a backrest. Of course it all depends on inseam, arm length, bars, etc.