2006 Ford Fusion Rear brake caliper piston

Hi all,

So I've been a lazy car owner and have waited a bit too long to replace my grinding brakes. Anyway, I knew that I would need a new rotor, so I got that and a new full set of pads, took the cap off the brake cylinder, and went to work at the car.

Well, apparently the caliper is set up in such a way as to make it impossible to get a C-clamp around it (at least in the size I have. And it's a big one) so that I can descend the caliper piston (as I've done in the past with many of my other cars). Anyway, I can't seem to get the darn thing down.I've tried prying it, though that is more difficult/dangerous.

So my question is this: have any of you figured out how to get it to descend easily? Also, for the Torque nuts on the rotor assembly, is that a T40 or a T45? Thanks in advance!