Frustrated with inability to do body work!

Raise the fender up so the lines on the side meet. That should open it up at the top of the door where the fender lays back towards the window post. I wouldn't grind the edges of the panels you'll end up going through. Not much meat there before you split the skin from the door or grind a hole in the fender. Hard to tell what you have going on there without standing right there.