How do you plan to drive the gate? Vgs is EVERYTHING. Until this number is nailed down, everything else is a guess.
At 3V on the gate, the device is only good for 2Amps - Maximum Rating, Page 2 - so somewhere less than that.
Look at Page 2 of the datasheet and pay attention to Note 7 for vias at the mounting pads. 2 Oz copper, etc.