Here is a bit more on the smoke system. What Im trying to do is:

1. Get the fuel as close to the CG as possible.
2. Make the smoke system removable at the field.
3. Keep everything as light as possible.

So this is what I came up with. A modular system where the fuel tanks and smoke system mount to removable panels of 1/8 carbon balsa sandwich that mount just in from of and under the wing tube. There are 2 setups - 1 with just a fuel tank (5oz) and one with 2 tanks and the smoke pump (13.5oz). I think the pictures explain it better than words can: