Thinking of Disneyland with my autistic child and worried?

My husbands family wants to take us to Disneyland in a couple months as a gift and a way to see them (they live near Disneyland in southern CA) It is extremely generous and my daughter is so excited to see Ariel, lol! BUT I am worried about my son. He is 3 years old and has autism. I am worried about sensory overload, the lines and too many people in general. I know I can't just keep him at home forever and he has to get used to places like this but I am still worried. I read on multiple sights to use ear muffs for sound, but he refuses anything to be on his head so that wont work and I am worried he wont tolerate the long lines for rides. Any tips, reurances or well, anything at all that would be great!