I just replaced my fender, and IIRC, there isn't any room for a wrench without taking the fender off. Taking it off shouldn't take you longer than a couple hours. First remove grill and front nose piece, second, loosen bolts behind nose piece (use some penetrating oil), and then the ones when you open the door. Lastly, remove the bolts that are in the engine bay.
When you're put everything back together, don't tighten it right up. You may find that there is a lot of slop to allow you to match the lines of the door, front nose.
HTH
Seth