This is indeed an ambitious project. Since you have already been lurking I would suggest you look around through the Finished Maps as well as Challenge Archives and see if maybe there is an existing map that 'catches your eye'.
You can then contact the author (FYI...you need at least 5 posts before you can use the private messaging feature) and see if they'll either (1) Allow you to use their previously existing map or (2) Be interested in creating a new one for you.
There are several folks here who regularly take on commissions, both paid & non (including myself) so I'm sure you'll find someone before to long to give you a hand.
You may even want to create a thread in the Map Request forum (be sure to follow the basic guidelines).