I used fiberglass resin jelly to fill in my bumper once. it took a really long time but it looked nice and it was the first time (technically second) I ever played with the stuff.
http://www.youtube.com/watch?v=4n6iNOxl5PA
at the very end, I used bondo just to smoothe it out. the area I covered was tons bigger than yours. I think you can do it in a day. just make sure to get the resin jelly (it is like grout and doesn't really drip) order it online if you can't find it locally. you won't need much at all. make sure to also have some paint. duplicolor seems to work well (also available online).
you can do this. save some money (you'll need it for the NOX setup ;))