My 2 cents (and my opinion only, not representitive of the CRG).
I have one other 68 SS in the DB with the D96 stripe (see below). Not great pictures, but you can clearly see the stripe going past the door into the rear quarter panel.
I also have a "late" (12-67 revision) order form and it states that D96 is "N/A on Camaro SS". I believe this was due to the "new" (January, 1968 release) D90 stripe which came down the sides of the car, and since the D96 ALSO came down the sides of the car, you couldn't have both, so therefore D96 was not available with SS.
However, earlier cars had the D91 Bumble Bee stripe which didn't come down the sides of the car, so I believe you COULD get the D96 with the SS at this point. Unfortunately, I don't have an early (pre 12-67) order form so I can't see what it says with regards to the D96 with SS. I also don't have the VIN on the car below, so that's no proof either.
I'm still looking at the pictures in the DB and hopefully I'll come up with more info.
Ed