Those mods look awwwful familar!
Definitely go for the wheel skirts for full batmobile effect. Nice work on the belly pan, but I feel like you're adding quite a bit of weight by going with wood. If wintertime in Detroit is anything like it is here (it is) then you're probably going to want that pan to be easily removed, as snow will find its way on top of the pan and just sit there, eventually rotting the wood. See if you can find a sign shop to give you some scrap coroplast and make the pan out of that instead.
Very nice work!