I guess I personally would phrase solipsism differently. Solipsism to me isn't just the belief that other people MIGHT be illustory, it's the position that they ARE. I wouldn't call someone a solipsist if they just had some small amount of doubt that everyone is real, I would call them a solipsist only if they claimed, "I am in fact the only real mind".
Maybe I've had a deep misunderstanding this whole time, but yeah, solipsism is a stronger claim to me than just having some doubt.