Here's what I was going to use.

http://www.regin.com/cart.html

I was going to mount it on my wingtip simply with a hose clamp at the leading edge, with a simple rocket motor igniter stuck in the back. I still have 4 of the orange 4 minute ones. They make a good bit of smoke and are real light.

5 for $25. Not bad at all really.

Does anyone know how to get around the AMA rule against them? Do you need a waiver?