I have a rusting screw secured with a U-style spring nut in a very tight and difficult place. The screw secures one of the fog light assemblies to the bottom of my Forester's bumper. Here's front and side views:
Trying to unscrew the screw using just a 10-mm wrench makes the whole thing rotate, bending the plastic. It is impossible to grip the nut, as the space is too tight for a standard pliers. Applying too much torque will surely crack the plastic. I sprayed with generous amounts of oil (WD40 style), but to no avail.
Is there a tool I can use to remove this stubborn screw?