I have a bone spur in my left shoulder so it looks like we're kind of in the same boat. I found this strap from a company called NeoTech. It's called a Wick-It bass strap. It's made from memory foam, like the Tempur-Pedic mattress'...It's just wide enough so that it rests on the flesh-y part of my shoulder with out actually riding on the shoulder bone so no pressure is put there. But it grips well and doesn't slide very much and is comfortable enough for me to weild a 8.25 pound Jazz bass that would not be do-able with any other strap.
I play in a Blues band and when we gig, the front man usually calls two 1 1/2 hour sets or three 50 minute sets, depending on the club. And this strap helps me get thru that with out any pain. Of course I will sit down for the occasional slow Blues tune to get off my feet, but I couldn't do this gig without this strap. Check out the link... )-(
http://www.neotechstraps.com/product...?PRODUCT_ID=28