Actually, they did.
You would have thought that most of the actual event and team vehicless them would have been LHD as they would have mostly been used in "drive on the right" countries.
However, the team vehicles were generally handed for the country of origin - for example, for the Camel Trophy in 1998 (the last event to use Land Rovers and the only one where I have the details off the top of my head) had RHD for the teams from South Africa, Japan and UK, whereas the rest were LHD.
The logic behind this is that although they were to be more familar with the drivers. And although they were "on the wrong side" for the event, it was afetr all, only a few weeks, whilst they might be used for event advertising and promotion for some time afterwards.
This can also be seen in the support vehicles and training/selection vehicles (often used for more than one event) which were a mix of left and right.
Cheers
Blippie