So the trick I use for rear rotors is this:
A little PB blaster at the lip of the hub. I actually use something called Kroil.
I get about an 18-inch long piece of 1 1/2 inch wood dowling (coat closet bar) and a 2-lb sledge hammer.
Hit the back side of the rotor (in the section where the caliper sits) with the hammer to the dowling. Rotate the rotor and hit it again. Go all the way around the rotor edge this way. It will pop right off (assuming you've released the P-brake).
Using a 2-lb sledge lets you use a low swing speed but still get a good amount of energy into the rotor. Using the dowling softens the blow to the rotor face and lets you resuse the rotor if you want, and allows for an open space to swing the hammer.