Unless you have a way to throw up another parking garage by October, they probably need to do both. Raise prices and increase capacity.
It's still insane to me that a multi-night ticket costs less than a single day ticket to many Disney parks and events.
Anecdotally, and feel free to disagree, I notice your crowd more than RJ's. After the first two weeks, Express runs pretty well. I don't feel like it's being overwhelmed. The streets however...
There aren't enough guests buying Express to back up parking like that.