I like the bandoleer approach myself, on the rare occasions I shoot SASS these days. My favorite is to use a US Cavalry M1912 pocket bandoleer, with 2 shells per pocket. Worn over the right shoulder it presents the shells perfectly to my left hand, while the relativly narrow strap does not interfere with the shotgun butt. (Rossi hammer double)
Now that my local clubs let me shoot GAF style, I don't use shotgun much anymore.