Hey fellow Wall-Hangaz!
Just my 2 cents on this, cause I’ve been looking into this myself recently 
I also like the Hercules Wall Hanger for Accoustic Guitars (GSP38WB), but my Shamisen alwas slipped through the hook and rested on the Sawari or the Itomaki 
So I wrapped some felt around the two hook-cushions and fixed them with needle and stitch.
I’m very happy with the result, it holds my Chuzao Minyō shamisen very safe And I personally like to have the Shamisen front facing me, so I was also very glad there is enough space to the wall.
On the pics you can see that I cut out some foam, especially on the position of the Sawari. This is from previous attempts where I thought the Shamisen would sink in deeper into the hook. With the felt like now, it’s not necessary to cut out foam.
Be aware that with “traditional” Shamisen Wall Hangers, the Instrument is showing me it’s back. However, I like my Instruments showing me their Face, I’m a Guitar Guy 
9d8d6029d5d06fb2fbf6405b6deb2cacc84026fa.jpg2448x3264 495 KB
e1971db8afcad5875a1106146b627784d507a38b.jpg3264x2448 459 KB
00cd3ee873d682a5441a16b39df792c756a41922.jpg2448x3264 476 KB
72c7545d1d18b7654ba2058ecbd171cd1b05658f.jpg3264x2448 509 KB
