I have been using a double layer of Rosco R-27 gel as a safelight filter and it has done well for me.
My darkroom has a recessed fixture in the ceiling. It has a regular 50 watt incandescent bulb. I took the frosted glass out of the frame sandwiched two layers of R-27 gel in there before putting the glass back in.
One layer of R-27 has a 4% transmission rating and, according to the company's charts blocks nearly all wavelengths shorter than 500-550 nm. The curve doesn't start toeing up until 600 nm. Putting a double layer of gel in the frame just gives a little more filtration.
The light in my room is a good 6 feet or more from any work area and you would have to stand directly under the fixture for any light to shine directly on anything.
While I am confident that my safelight is good for at least 15 minutes under normal working conditions I am still careful to bring paper out of its container for only the minimum amount of time needed to perform the task at hand. I have a spare empty box left over from a previous batch of photographic paper that I use as a makeshift paper safe. If I have paper out any longer than is necessary to print and develop, it goes in the box/paper safe.
I also keep my paper safe in a drawer and my fresh paper stock in another drawer. Those drawers are closed at all times except when I am actually taking something out or putting them in and I never open those drawers unless the room is under safelight or complete darkness.
Aside from providing protection from safelights that may or may not be completely safe, it also helps minimize damage in case the door gets opened or the white lights get turned on by accident.