Have you considered a fly reel. They are very light weight and can easily be loaded up with 200 yards of braided line. If you had a remote servo to release the spool it could be left in free spin. the sinker/weight could be dropped to the person (provided they are conscious) then flown back to the SAR point.
A fly reel is designed to be buttery smooth, you just need a way to remotely release the spool. There should be a servo or switch that would work with a fob at 200 yards.
Just thinking outloud.
