6 months seems like a long time to coast. Seems like the schools should be willing to do something in the meantime...although I totally get not wanting to go through the pain of advocacy. I just know that my son can talk a great line, but in the end, he is still a child, and not so great at 'Know Thyself.'
Does your DD8 get much homework? If not, and she is just loving the social aspect of school and motivated to finish the year, why not 'insist' on 15 minutes of homework on the nights she doesn't get any from school? Or be very agressive about letting the teacher know that you won't be requiring her to do homework that isn't at her readiness level, but will be substituting your own for your daughter to hand in?
I appreciate the thoughts as we're still trying to figure out how best to handle this year. It's a long and convoluted story really, probably deserving a new post. Overall though it has been more a shift in her focus. Her primary issue is with not feeling challenged in math. This has been an issue since day one at the school.
We have not stopped advocating for her, though admittedly if we were planning on having her back at the school next year we would be doing lots more. She has decided instead to put her focus at school into other areas and not in math. She has been enjoying project studies they have been doing and loves a number of her special classes. It just happens that math is her favorite subject and the one in which we struggle to find challenge for her in school.
It does not help that the school's solution this year is to supply her with at home, optional enrichment. She has enough at home materials already. It only further convinced her she should be learning at home.

Our biggest concern the first few months of school this year was how her frustration with math at school extended to not wanting to do anything else at home for fear of getting further ahead. Since she made the decision to not expect challenging math at school and to school at home next year this has changed. She still has no desire to do the optional work sent home by the school but is going back to doing some of the at home enrichment we have here. She just won't tell her school she's doing them.
It's helped that I've begun doing some of DD5's k12 work in the evenings. DD8 jumps right on in and we have to get creative with her. It's been a nice trial run in a way. I do know that I should push ODD a little more then I do because actually we never really have. She's always been self motivated when it comes to her learning.
Thanks again!