hmmm ... try this
create a column of empty vehicles
create a squad of drivers
create a whole bunch of squads as passengers
the drivers and passengers all have the camo you really want.
the drivers get assignAsDriver/moveInDriver commands
the passengers get moveincargo commands
the drivers (in one squad) will drive in convoy if you make the first move waypoint formation column. behaviour safe usually helps too. The order of the vehicles will be the order of squad number - 1 at the front, then 2 etc with 12 at the back. This may be the same as rank.
on ambush, use switch triggers to give the passengers get out waypoints
meanwhile, the drivers are awarded git-the-hell-out-of-here waypoints
if get out waypoints don't work, try unAssignVehicle commands for the passengers as well
that should leave you with passengers on the ground and drivers still in their vehicles
I can't have empty vehicles with them inside because then I couldn't have the soldiers AND the crew in at the same time - if I do that, either the troops or the crew automatically leave the vehicle.
I don't understand this bit.