Bad idea.
An isolated ground is simply a ground wire that runs straight from the device to the panel, without connection to other ground wires along the way. Since you're running a dedicated circuit, the usual ground wire will do just fine.
Heck, with plastic boxes, you don't even need a fancy IG receptacle. The yoke is never in contact with anything that's also grounded. Just connect the ground wire to the screw on the receptacle.
