From the Official How to Make A Map thread:
Step 2). Image Creation——Create a visual layout of the map. Include a working legend with speculative bonuses, tentative border divisions, names, barriers, colors and textures, aesthetic images (I.E. compasses, picture designs, etc), and background image (I.E. ocean or something to discriminate the playing field). A map should be ‘inherently unique either in gameplay, location, or style’ . Maps that aren't just the same tried and true formula from the Classic Map disguised will be more successful. Host the image using Photobucket.com or something similar. The type of image file must be PNG, GIF, or JPEG. You must design two versions of the map: a small (up to 600 px wide), and a large (up to 800 px wide). Height is flexible, but it is recommended that you do not exceed 350 px on small maps and 600 px on large maps so that users will not need to scroll down to attack.
So yes it's possible and something I'd like to see done if it's done tastefully and doesn't create too much of a distraction. I think you're one of the few people that could pull it off WidowMakers.