It may be too early to tell with certainty, but I started using
Mobil 1™ High Mileage 10W-40 instead of the BMW high perf oil 5W-30 and, to my delight, noticed much reduced smoke and much, much reduced oil consumption! For the first time since this issue started I have seen the oil in deep stick stay at half mark after a long drive (300 miles). Keeping my fingers, toes, balls crossed that this lasts, at least till my next scheduled oil change (5k miles). Bought 3 gallons of the oil from Walmart at $23 per gal.