Even the earliest A Models had the ability to rig the Cargo Winch to work at the aft end of the ramp in a rescue mode or if the cargo hook had been removed....thru the access hatch over the Cargo Hook.
Some aircraft had been fitted with external Rescue Hoists over the years.
Remember the Mission Set for the Chinook generally was not as a dedicated SAR or Medical Evacuation aircraft where such winching would be part of the operational use for the aircraft.
We tended to do mass casualty flights where we landed and loaded Litters or floor loaded wounded or a combination of both.
Rotor Wash velocities can trigger Mines/Booby Traps/Trip Flares.