I'm pretty much out of handlebar read estate, plus the bell clamp didn't want to play nicely with my drop bars; the clamp wasn't large enough.
So, I unscrewed the bell mount assembly, chucked it, and screwed the bell + ringer arm directly into the downtube shifter boss.
When I had my tuneup this winter, I asked the mechanic if I was asking for trouble with this arrangement, because the bell screw is shorter than the screw that was originally in that location. He said nope, it was fine, and if it wasn't, I'd have known immediately.
I had thought about ordering one of those headset spacer + bell mount combos from Velo Orange, but since this solution was free and works just fine, I'm sticking with it. I do occasionally reach down and make sure that the bell is still firmly screwed on. I should probably Locktite it down.