Well one thing to consider is, that at least some (most likely all) of those guys were racing Cape Epic themself and not just race it, but placed in top 5 teams not more then 3 or 4 years ago. So most of them could almost follow top teams on normal bikes
Otherwise I would say with so big organization and such budget it should be fairly easy to handle this logistics. There's few extra bikes and on water stations those guys just hop on new bikes with fresh batteries and continue coverage. But I agree, it was cool to see that footage from follow bikes and not just chopper.