Sure, you could slap a plug on this and plug connect the power supply to the EVSE like the Leviton units do. This unit is nice, but it doesn't support the full 30 Amps for future vehicles like a future LEAF Gen 2 or the Ford Focus Electric that can charge at 6.6 kW. I will support the full 3.3 kW charge rate of the current LEAF. The other thing is that in protable use, this unit is 240V only.
The http://evseupgrade.com/ unit charges the LEAF slightly slower (87%) at 2.8 kW instead of the max 3.3 kW of the current LEAF. But it has the distinct advantage of using 120 or 240V, so it can take advantage of whatever power source is available. It is low volume, and while quality constructed from UL Listed components, the modified unit is not UL listed, if that matters to you. (Like if you replace an old plug on a lamp, you will void the lamp's UL Listing.)
