Something like this is what I was thinking, but I don't have any of the boxes yet either and can't invest in that right now. I got my half price apache case yesterday and will use that for now.
My 570 has this bracket that the factory hip bar mounts to. The instructions say to unbolt and remove the bar, but it doesn't say anything about this bracket. It looks like it has to go for the door to line up correctly.
I also looked at the SuperAtv doors and noticed that their web page pictures are of an 800 without that bracket. Their instructions show the bracket but in the finished product it's a different rig with a custom cage so no bracket.