I have and still use a monopod made by the old Daylite Screen company,
It looks like Bat Masterson's gold top cane. I have never been stopped by the museum authorities or even asked not to use it. They work better than
hand held, but a tripod is still the only way to go if possible. A bean bag is
not my cup of tea, they are hard to carry, work great, but take up too much space for me. I began using one while shooting the old Denver bronco's football games, A 180 mm was norm then, and nose heavy so the monopod
mounted to the lens socket (1/4x20T) helped balance the camera body very well. I also use a walking stick carved out of a hard wood stick with a quarter twenty machine screw epoxied into the top for primitive rendezvous and Civil War reenactment. These folks dont want to see a bright shiney modern anything in their camps. (And rightly so!)