I would think that you might get more of a gain with the wheel skirts, but as you said a belly pan will help with warm up times as well.
When figuring out wheel skirts, check how much clearance you need to get the wheels off, with the new (updated) skirts on mine, I went about as low as I could while still being able to take the wheels off easily. This way I don't have to mess with the skirt anytime I want the wheel off.
Oh, and get them done by the 20th I want to check them out!
__________________
|