Old air cooled twins would still have been a better bet though! Small enough that they could easily have fit a couple of spare bikes in the support vehicles but large enough to carry luggage.
I don't think even BM would have supported a RTW ride on models they no longer sold.
The 1150GS's used on TLWR were air/oil cooled and about as simple a load-lugging 'big' bike as you could get.
Almost anywhere in the known world, the girl from the local chippy can fix an 1150 with not much more than a fish slice and a bucket of used chip oil and any farmer worth his salt can re-weld the sub-frames when they (always) break.
By the time it was TLWD, BM were flogging 1200GS's and so the complexity grew.
Either way it made BM's fortune and sold a gazillion GS's to RTW wannabe's.
As for support vehicles...you mean it wasn't just the two of 'em and the camera man?