Paul,
If you really want to be a sicko about it, since the part of the pencil holder that faces the snare drum/tom etc is mesh, you can put a windscreen over it! There may even be some that have elastic in them so that you can stretch it right over the pencil cup holder. I'm thinking maybe one of those furry ones would do the trick.
Or one of the think foam ones would fit right into the base of the pencil cup holder, you'd probably have to cut it to size but it would definitely work.
You could also do the same thing with the drawer that goes over the LDC.
Seriously, it took me a bit of searching around on google shopping to find this stuff and then just a bit of some imagination and this idea came to fruition. I find it really strange that there isn't a manufacturer out there who has made this into a product. If I see somebody next week selling these things, well remember who made it public first!
If I have some free time, I'll see if theres a way it could clip directly to a SDC or it could fit around an SDC like a shockmount. That would require a little bit more mechanical alteration though and wouldn't be as simple as this design though. However it would serve several purposes at once.
I would love to offer this as a product with our tube SDC line!
Peace
Illumination