Parent of dysgraphic here. Got a 504 and lots of advocacy was required to get it followed. It is not going to be smooth. A 504 is nothing without advocacy.
Is it a PIA to advocate? YES! Is it fair? NO! What about kids who don't have squeaky parents?
Don't be quick to write people or schools off. When you get negativity, respond with how it makes your child feel-- no teacher wants to make a kid feel bad. When there are logistical problems, help them work it out. If there are things he's not learning, teach him yourself so he can show what he knows. Solve problems yourself to help them out.
My kid was an "unpleasant" personality so not one that people wanted to go out of their way for. But they still did it. With advocacy and parent support.