The use of lifelines for wayfarer cruising usually has opinion divided. On the one hand the lifeline restricts your movement while sailing the boat, making a mistake more likely. On the other hand if one of the crew were to go overboard the chances of recovery when sailing on the open sea in testing conditions would be poor. At night even worse.
We tend to sail with lifelines if we on the open sea, and as soon as conditions get a bit lively then we will clip on. On the rare night passages then lifelines are on irrespective of conditions.
We use normal yacht harnesses. In the past I have used a harness built into a jacket.
The “line” is lifeline webbing, a Gibb clip to attach to the harness end. The boat end is a soft eye taken through a strong part of the boat – eg tabernacle, toe straps. I guess they are about 3m long. I don’t think you want it too long, it will just get tangled.
The Gibb clips are easy to un-clip when you want to.
We have sailed off the West coast of Scotland many times and harnesses are always taken.
hope that helps