For tyhe flag, you can use a length of wood dowel or conduit pipe cut to the width of the flag. Then get yourself a grommet kit and set them about 12-16" apart (depends on the size of the flag or course). You can use rope, zip ties, whatever ya like to fasten it to the rod/pipe, my preference is to use clips affixd to the rod/pipe so it looks better and is more permanent.
As far as hanging it from the ladder, run a line from each end up to the corner of your ladder, again I'd use clips for ease of mounting and good looks. And to keep the flag steady in a breeze you could either run lines to hook to the cab or weights.
And yes, I have done this before, just with a flag that could cover a house.
Made a few monster banners as well.
