I helicoiled mine last fall. Did the 2 holes for the plate at the same time. It seems to me I even stacked 2 coils for the AFC housing because the holes are deep enough, though you can't get the entire second coil all the way in. I just filed it a bit where I wanted it to break off, screwed it in to the top of the first coil, then snapped off the part that stuck out at my filed notch using a pair of needle nose pliers.
As for the upper forward one under the lines, yes it can be booger. I replaced all mine with allen head screws then got a ball-head allen wrench that goes on my 1/4" ratchet. I smoothed off the ridges on the length of the allen wrench using the grinder so it won't chew up the lines.
But realistically, as Forrest said, you can go without that screw just fine and save yourself the hassle.
-Jay