Of course, BMW doesn't recommend it.
I never had any driveshaft issues on my '12 GTL up to 60,000 miles, some of that pulling rather large trailers. Nor on my '13 GTL, even after pulling 1,100 lbs at freeway speeds for a thousand miles up I-5.
Now I did get a notchy u-joint on my K1300GT at around 60,000 miles, but that bike has never pulled a trailer...
Ken IBA# 366
'13 Dark Graphite Metallic K16GTLD
Some people see the gas tank as half empty. Some see it as half full. All I care is that I know where the next tankful is coming from . . .