Torre Straps will be making a custom one of these for me later in the month:
https://www.instagram.com/torrestrap...en&img_index=1
I can report back on the softness once it has landed.
I have a Jurgen grey Bund on my KSK (left one below) which is quite soft though a tad bulky. The only caveat I would add is that he's been kicked off MWR for a reason that escapes me.
My other thought would be a Kaufmann Bund but, looking at their website, it's not clear that they still make them.