Configuring subpixel-layout per monitor is something that most OS won't allow. So if you use several monitors, you usually have to mount the BGR-ones upside down. (Otherwise fonts will be blurry...)
For some time now there are really cheap 4K Monitors with BGR-layout available. If you mount those upside down you're fine... (I use LG 4K Monitors mounted upside down in combination with other screens)