It really dosen't matter if it a tempory tent or permanent building (like a remodel). The panel IAW the OP is temporary that is fed with a feeder, not a drop or lateral therefore the service feeding the temp panel via a feeder, in theory is already grounded. Since the OP is being fed with a 3 wire with ground, presuming that it everything is properly connected, a ground rod is not required. Not to say one can be added but it need to be bonded to the service ground. The devil is in the definitions not the details.
