My understanding is that it would be something of a nightmare; at one of the early "ride in" events I was told to order extended electrics, safari roof and lockers, if you wanted them, as it would be very, very difficult to add them later. (I didn't get the lockers, as I probably would never use them).
A conversation with an auto-electrician would be a good idea - depending on what you want they could customise what you want based on factory bits. The guys who put my dash cam in thought the Grenadier was very well laid out and quite easy to get extra wires into.