Well, yes it is simply plug and play, in theory. In practise, you can run the Engel fridge for about two days and nights before worrying about power. With the vehicle at a standstill and fully charged batteries that is. If you don't want to use it for camping out and about, no worries. There is plenty of power for a day or two with the dual batteries.
There don't seem to be any details available on how the two (or three?) batteries are wired/setup on the Grenadier, i.e. whether the fridge will drain both batteries and potentially keep you from starting the vehicle. On a professional setup, the two batteries are being separated mechanically, electrically or electronically when "leisure power" is required without the engine running. That has yet to be seen - and can be retrofitted if required and not there.
One way or the other, you can't go wrong with the SB 30, the wiring supplied with it will most likely reach a socket anywhere in the back, the 12v cable is of substantial quality and some 2 or 2,5m long.
A Toyota factory setup w dual batteries is hopeless with that task, for instance. You'll need a new set of batteries every couple of months (or even weeks)..
