Do you have a union? I wonder if this is something they could help with. If it's anything like my district, the district union people wouldn't know much, but they could push it to someone higher up within the union who would have more familiarity with sped.
We don't have caseload limits in my state, so I'm no help there

. At one point I had almost 50 kids and was told it was fine because I had a part time para. People just have no idea.
Two years ago, my P non-renewed our school psych and we couldn't find anyone. There were only a couple of applicants. P didn't want one of them and the other turned the job down when she realized the salary vs. COL (she was from out of state).
My district went through some sort of head hunting agency to find a replacement after we still didn't have someone by October. It's more expensive than just hiring someone directly, but they guarantee to fill the position. Perhaps you "helpfully suggest" that, in writing?