I pull a 30' Toy Hauler trailer and we are also avid BMW motorcyclists. We always show appreciation when someone is kind enough to pull over to let us pass on the bikes. When towing, we do what the OP does, pull over when safe to let others pass.
What galls me are the people who tow on beautiful curvy roads with many opportunities to pull over but just continue to go on. There are times when, in frustration, I pull the bike over and let the "blocker" get miles ahead of us so we can enjoy the road.
Off soapbox now