One thing to keep in mind when long lining with a twin is that when the donkey resigns and you punch off the load, if not the long line too, you are left with a helicopter that has I person aboard, probably a small fuel load and that’s all. Hence your mass is pretty low and you’ll probably have very reasonable OEI performance.
We had one fellow lose an engine in a AS335 in such circumstances and it was a non event he did pull full OEI temp limits as it was a very hot day.
Another in a 212 with -3B engines and he didn’t even need to pull OEI power to recover and return to base with his 200’ LL still attached. He was working over jungle with 180’ trees and the long line was about 10’ feet from the jungle floor when it happened. 500 ASL, 0 wind, 30 C. It was “Calm, cool and collective” that day as the “Stud Duck” AKA the chief pilot said.