There is a limit to adjusting base idle. BMW doent give you much adjustment. Definately not to 1500 rpm! It is still burning oil. You just dont notice it as much at that rpm. The reason your plugs are not fouling and there is no smoke on cold start is because the exhaust valve seals are usually the ones that leak. The hot exhaust gasses burn the oil leaving the combustion chamber. Typically the engine needs to be at normal operating temperature. Then let it idle for like 10 minutes. Then blip the throttle up to like 4k rpms a few times. When the valve seals get really bad it will look like a smoke machine at idle. You will see the carbon build up in the exhaust ports of the head and the exhaust manifolds. Do them sooner than later or you will be buying catalytic converters too.
What ports are you plugging? CCV? If so, dont think that will help your situation.
My guess is if you eliminated ccv on your engine and are running catch cans, your smoking issue is not ccv.