This is a case where, besides gaining access to the area, "get a bigger hammer" is the actual answer.
I just replaced my fan clutch, for the second time, in my '89. Unfortunately mine doesn't have a serpentine belt. A/C, PS and alternator had to be loosened to properly get to the clutch.
Many people do not realize smacking a wrench with a hammer is akin to using an impact wrench; hence the name.
Never pry on a bolt. Prying continuously stretches the bolt. Smacking it with a hammer or using a real impact stretches it for just a second and allows it to spring back. You'll get much fewer broken bolts that way.
Also, don't forget some screws, bolts, etc, will come off easier if you tighten them just a little before attempting to loosen them.
One more thing.
An impact gun loses much of its effectiveness the more extensions, universals, etc, are between the gun and the bolt. A good case in point is the driveshaft bolts on my '89. They take a 12mm 16pt socket. My impact wrench is rated at 650lbs in reverse. It will not budge these bolts unless the socket is directly attached to the impact gun.