Thanks for everyones feedback, as expected the opinions vary as much as the available options to choose from.
Given that the question was purely about Resale Value, and what specifications would be preferred to the someone looking to pick up one in the 2nd hand market, I am of the following opinions,
Firstly - People will generally like the idea of the special Belstaff Editions - as they are a known quantity of additional options that are included in the vehicle.
Secondly - A potential buyer will be looking for a car with the three options that you cannot do as an aftermarket fitment - Lockers, Sunroof, Electrical Preparation.
Thirdly - In Australia, car owners will typically prefer a car with Leather and Sunroof - even if they don't need them, and if they are wanting Leather/Sunroof, then they would also expect a car to have alloy wheels.
So this in my book leads to the conclusion that a Fieldmaster, with Rough Pack and Electrical Preparation is probably the vehicle that ticks most of the boxes.
This also ticks the following boxes:
That a lot of people will be looking at this car as a decent vehicle that can tow their large caravan touring the black top, so the extra "Style" options of the Fieldmaster will be more desirable to the towing market - not everyone in this market will like the look of the Air Intake/Cloth Seats etc, or will want a winch etc.
It is still a cracking 4x4 in its own right which can still do more that most people will ever ask of it.
That in the above configuration it competes extremely favourably against the top end of the Landcruiser 300 series as far as specification level, however costs perhaps around $45,000 less. A SW (irrespective of the the options on it), will still be compared in peoples minds with a base level GX LC300, or LC70 Series.
People who want one immediately, and don't really want to wait, probably are looking more at the higher price bracket, rather than the lower pricing bracket.
That people who who are serious about ordering an IG to their unique specifications, colours etc, will not buy a 2nd had one anyway, but will specify their own and wait for their own unique vehicle.
Anyway, these are my current thoughts.