I've had one of those stiff rubber block sandpaper holder things forever, and always hated trying to pry the top back to get the sandpaper over the little nails. Saw this on an endcap at Lowe's, today - a computer-mouse shaped sanding block with hook&loop attachment for 5" round paper. So you can use the same (or worn) paper from your 5" ROS for hand sanding. And the ergonomics are fantastic. I threw the hard rubber block away.
I can't find it anywhere on the internet, though, despite searching the product code, the UPC code, etc. So hopefully you can find one at Lowe's