2e DS11 gets extended time under his 504. Any suggestions on where this should come from? Right now he stays in from recess to finish things but that seems unfair. And if it isn’t recess it is getting excused from assignments in his areas of strength so he can spend more time finishing his assignments in his area of weakness.

The school is being cooperative with any suggestions I have so I’m looking for something that’ll maybe work better.

Try reduced workload instead of/in combination with extended time. As I just described on another thread a few seconds ago, I'd suggest "starred items only, sufficient to demonstrate mastery of standards," and, possibly, "essential assignments only".