I have the BB with and use the orange carboy caps. I just put a piece of vinyl tubing onto one of the stems that stick out of the carboy cap. I haven't had any crazy fermenting beers in there yet so the smaller diameter tubing was good. I also haven't dry hopped a vigorously fermenting beer, but I'm thinking a larger tube may be needed for that. My caps don't seem to seal right either so I wrap them with the plastic stretch wrap you get at home improvement stores for bundling materials, so even if there were a lot of force against the cap it won't come off. You might be able to use some of that around your current blow off to secure it to the top of the bottle, sanitized of course.