I made a script that will automatically download and install GPULightmass on your binary installation folder, perform a batch of checks to avoid issues (like nvidia driver version and TdrDelay), and allow to change GPU bake quality among fast, medium, high, extreme, without the need to restart Unreal.
If it helps someone, just give me a “Like” below.
UPDATE 12/11/2018: Now updated to work with 4.21 (Unified Settings). Allows to chage settings on the fly between different BaseLightmap.ini configurations.